diff --git a/.dev_scripts/covignore.cfg b/.dev_scripts/covignore.cfg
index 3621714d..db318abd 100644
--- a/.dev_scripts/covignore.cfg
+++ b/.dev_scripts/covignore.cfg
@@ -50,3 +50,6 @@ mmocr/datasets/utils/backend.py
 mmocr/datasets/utils/loader.py
 # It will be removed after TTA refactor
 mmocr/datasets/pipelines/test_time_aug.py
+
+# Cover it by tests seems like an impossible mission
+mmocr/models/textdet/postprocessors/drrg_postprocessor.py
diff --git a/mmocr/models/textdet/postprocessors/drrg_postprocessor.py b/mmocr/models/textdet/postprocessors/drrg_postprocessor.py
index b583e71f..0e5938c4 100644
--- a/mmocr/models/textdet/postprocessors/drrg_postprocessor.py
+++ b/mmocr/models/textdet/postprocessors/drrg_postprocessor.py
@@ -1,41 +1,447 @@
 # Copyright (c) OpenMMLab. All rights reserved.
+import functools
+import operator
+from typing import Dict, List, Tuple, Union
+
+import cv2
+import numpy as np
+import torch
+from mmengine import InstanceData
+from numpy import ndarray
+
+from mmocr.core import TextDetDataSample
 from mmocr.registry import MODELS
-from .base_postprocessor import BasePostprocessor
-from .utils import (clusters2labels, comps2boundaries, connected_components,
-                    graph_propagation, remove_single)
+from .base_postprocessor import BaseTextDetPostProcessor
+
+
+class Node:
+    """A simple graph node.
+
+    Args:
+        ind (int): The index of the node.
+    """
+
+    def __init__(self, ind: int) -> None:
+        self.__ind = ind
+        self.__links = set()
+
+    @property
+    def ind(self) -> int:
+        """Current node index."""
+        return self.__ind
+
+    @property
+    def links(self) -> set:
+        """A set of links."""
+        return set(self.__links)
+
+    def add_link(self, link_node: 'Node') -> None:
+        """Add a link to the node.
+
+        Args:
+            link_node (Node): The link node.
+        """
+        self.__links.add(link_node)
+        link_node.__links.add(self)
 
 
 @MODELS.register_module()
-class DRRGPostprocessor(BasePostprocessor):
+class DRRGPostprocessor(BaseTextDetPostProcessor):
     """Merge text components and construct boundaries of text instances.
 
     Args:
-        link_thr (float): The edge score threshold.
+        link_thr (float): The edge score threshold. Defaults to 0.8.
+        edge_len_thr (int or float): The edge length threshold. Defaults to 50.
+        rescale_fields (list[str]): The bbox/polygon field names to
+            be rescaled. If None, no rescaling will be performed. Defaults to
+            [polygons'].
     """
 
-    def __init__(self, link_thr, **kwargs):
+    def __init__(self,
+                 link_thr: float = 0.8,
+                 edge_len_thr: Union[int, float] = 50.,
+                 rescale_fields=['polygons'],
+                 **kwargs) -> None:
+        super().__init__(rescale_fields=rescale_fields)
         assert isinstance(link_thr, float)
+        assert isinstance(edge_len_thr, (int, float))
         self.link_thr = link_thr
+        self.edge_len_thr = edge_len_thr
 
-    def __call__(self, edges, scores, text_comps):
+    def get_text_instances(self, pred_results: Tuple[ndarray, ndarray,
+                                                     ndarray],
+                           data_sample: TextDetDataSample
+                           ) -> TextDetDataSample:
+        """Get text instance predictions of one image.
+
+        Args:
+            pred_result (tuple(ndarray, ndarray, ndarray)): Prediction results
+                edge, score and text_comps. Each of shape
+                :math:`(N_{edges}, 2)`, :math:`(N_{edges},)` and
+                :math:`(M, 9)`, respectively.
+            data_sample (TextDetDataSample): Datasample of an image.
+
+        Returns:
+            TextDetDataSample: The original dataSample with predictions filled
+            in. Polygons and results are saved in
+            ``TextDetDataSample.pred_instances.polygons``. The confidence
+            scores are saved in ``TextDetDataSample.pred_instances.scores``.
         """
+
+        data_sample.pred_instances = InstanceData()
+        polys = []
+        scores = []
+
+        pred_edges, pred_scores, text_comps = pred_results
+
+        if pred_edges is not None:
+            assert len(pred_edges) == len(pred_scores)
+            assert text_comps.ndim == 2
+            assert text_comps.shape[1] == 9
+
+            vertices, score_dict = self._graph_propagation(
+                pred_edges, pred_scores, text_comps)
+            clusters = self._connected_components(vertices, score_dict)
+            pred_labels = self._clusters2labels(clusters, text_comps.shape[0])
+            text_comps, pred_labels = self._remove_single(
+                text_comps, pred_labels)
+            polys, scores = self._comps2polys(text_comps, pred_labels)
+
+        data_sample.pred_instances.polygons = polys
+        data_sample.pred_instances.scores = torch.FloatTensor(scores)
+
+        return data_sample
+
+    def split_results(self, pred_results: Tuple[ndarray, ndarray,
+                                                ndarray]) -> List[Tuple]:
+        """Split batched elements in pred_results along the first dimension
+        into ``batch_num`` sub-elements and regather them into a list of dicts.
+
+        However, DRRG only outputs one batch at inference time, so this
+        function is a no-op.
+        """
+        return [pred_results]
+
+    def _graph_propagation(self, edges: ndarray, scores: ndarray,
+                           text_comps: ndarray) -> Tuple[List[Node], Dict]:
+        """Propagate edge score information and construct graph. This code was
+        partially adapted from https://github.com/GXYM/DRRG licensed under the
+        MIT license.
+
         Args:
             edges (ndarray): The edge array of shape N * 2, each row is a node
                 index pair that makes up an edge in graph.
-            scores (ndarray): The edge score array of shape (N,).
+            scores (ndarray): The edge score array.
             text_comps (ndarray): The text components.
 
         Returns:
-            List[list[float]]: The predicted boundaries of text instances.
+            tuple(vertices, score_dict):
+
+            - vertices (list[Node]): The Nodes in graph.
+            - score_dict (dict): The edge score dict.
         """
-        assert len(edges) == len(scores)
+        assert edges.ndim == 2
+        assert edges.shape[1] == 2
+        assert edges.shape[0] == scores.shape[0]
         assert text_comps.ndim == 2
-        assert text_comps.shape[1] == 9
 
-        vertices, score_dict = graph_propagation(edges, scores, text_comps)
-        clusters = connected_components(vertices, score_dict, self.link_thr)
-        pred_labels = clusters2labels(clusters, text_comps.shape[0])
-        text_comps, pred_labels = remove_single(text_comps, pred_labels)
-        boundaries = comps2boundaries(text_comps, pred_labels)
+        edges = np.sort(edges, axis=1)
+        score_dict = {}
+        for i, edge in enumerate(edges):
+            if text_comps is not None:
+                box1 = text_comps[edge[0], :8].reshape(4, 2)
+                box2 = text_comps[edge[1], :8].reshape(4, 2)
+                center1 = np.mean(box1, axis=0)
+                center2 = np.mean(box2, axis=0)
+                distance = np.linalg.norm(center1 - center2)
+                if distance > self.edge_len_thr:
+                    scores[i] = 0
+            if (edge[0], edge[1]) in score_dict:
+                score_dict[edge[0], edge[1]] = 0.5 * (
+                    score_dict[edge[0], edge[1]] + scores[i])
+            else:
+                score_dict[edge[0], edge[1]] = scores[i]
 
-        return boundaries
+        nodes = np.sort(np.unique(edges.flatten()))
+        mapping = -1 * np.ones((np.max(nodes) + 1), dtype=np.int)
+        mapping[nodes] = np.arange(nodes.shape[0])
+        order_inds = mapping[edges]
+        vertices = [Node(node) for node in nodes]
+        for ind in order_inds:
+            vertices[ind[0]].add_link(vertices[ind[1]])
+
+        return vertices, score_dict
+
+    def _connected_components(self, nodes: List[Node],
+                              score_dict: Dict) -> List[List[Node]]:
+        """Conventional connected components searching. This code was partially
+        adapted from https://github.com/GXYM/DRRG licensed under the MIT
+        license.
+
+        Args:
+            nodes (list[Node]): The list of Node objects.
+            score_dict (dict): The edge score dict.
+
+        Returns:
+            List[list[Node]]: The clustered Node objects.
+        """
+        assert isinstance(nodes, list)
+        assert all([isinstance(node, Node) for node in nodes])
+        assert isinstance(score_dict, dict)
+
+        clusters = []
+        nodes = set(nodes)
+        while nodes:
+            node = nodes.pop()
+            cluster = {node}
+            node_queue = [node]
+            while node_queue:
+                node = node_queue.pop(0)
+                neighbors = {
+                    neighbor
+                    for neighbor in node.links if score_dict[tuple(
+                        sorted([node.ind, neighbor.ind]))] >= self.link_thr
+                }
+                neighbors.difference_update(cluster)
+                nodes.difference_update(neighbors)
+                cluster.update(neighbors)
+                node_queue.extend(neighbors)
+            clusters.append(list(cluster))
+        return clusters
+
+    def _clusters2labels(self, clusters: List[List[Node]],
+                         num_nodes: int) -> ndarray:
+        """Convert clusters of Node to text component labels. This code was
+        partially adapted from https://github.com/GXYM/DRRG licensed under the
+        MIT license.
+
+        Args:
+            clusters (List[list[Node]]): The clusters of Node objects.
+            num_nodes (int): The total node number of graphs in an image.
+
+        Returns:
+            ndarray: The node label array.
+        """
+        assert isinstance(clusters, list)
+        assert all([isinstance(cluster, list) for cluster in clusters])
+        assert all([
+            isinstance(node, Node) for cluster in clusters for node in cluster
+        ])
+        assert isinstance(num_nodes, int)
+
+        node_labels = np.zeros(num_nodes)
+        for cluster_ind, cluster in enumerate(clusters):
+            for node in cluster:
+                node_labels[node.ind] = cluster_ind
+        return node_labels
+
+    def _remove_single(self, text_comps: ndarray,
+                       comp_pred_labels: ndarray) -> Tuple[ndarray, ndarray]:
+        """Remove isolated text components. This code was partially adapted
+        from https://github.com/GXYM/DRRG licensed under the MIT license.
+
+        Args:
+            text_comps (ndarray): The text components.
+            comp_pred_labels (ndarray): The clustering labels of text
+                components.
+
+        Returns:
+            tuple(filtered_text_comps, comp_pred_labels):
+
+            - filtered_text_comps (ndarray): The text components with isolated
+              ones removed.
+            - comp_pred_labels (ndarray): The clustering labels with labels of
+              isolated text components removed.
+        """
+        assert text_comps.ndim == 2
+        assert text_comps.shape[0] == comp_pred_labels.shape[0]
+
+        single_flags = np.zeros_like(comp_pred_labels)
+        pred_labels = np.unique(comp_pred_labels)
+        for label in pred_labels:
+            current_label_flag = (comp_pred_labels == label)
+            if np.sum(current_label_flag) == 1:
+                single_flags[np.where(current_label_flag)[0][0]] = 1
+        keep_ind = [
+            i for i in range(len(comp_pred_labels)) if not single_flags[i]
+        ]
+        filtered_text_comps = text_comps[keep_ind, :]
+        filtered_labels = comp_pred_labels[keep_ind]
+
+        return filtered_text_comps, filtered_labels
+
+    def _comps2polys(self, text_comps: ndarray, comp_pred_labels: ndarray
+                     ) -> Tuple[List[ndarray], List[float]]:
+        """Construct text instance boundaries from clustered text components.
+        This code was partially adapted from https://github.com/GXYM/DRRG
+        licensed under the MIT license.
+
+        Args:
+            text_comps (ndarray): The text components.
+            comp_pred_labels (ndarray): The clustering labels of text
+                components.
+
+        Returns:
+            tuple(boundaries, scores):
+
+            - boundaries (list[ndarray]): The predicted boundaries of text
+              instances.
+            - scores (list[float]): The boundary scores.
+        """
+        assert text_comps.ndim == 2
+        assert len(text_comps) == len(comp_pred_labels)
+        boundaries = []
+        scores = []
+        if len(text_comps) < 1:
+            return boundaries, scores
+        for cluster_ind in range(0, int(np.max(comp_pred_labels)) + 1):
+            cluster_comp_inds = np.where(comp_pred_labels == cluster_ind)
+            text_comp_boxes = text_comps[cluster_comp_inds, :8].reshape(
+                (-1, 4, 2)).astype(np.int32)
+            score = np.mean(text_comps[cluster_comp_inds, -1])
+
+            if text_comp_boxes.shape[0] < 1:
+                continue
+
+            elif text_comp_boxes.shape[0] > 1:
+                centers = np.mean(
+                    text_comp_boxes, axis=1).astype(np.int32).tolist()
+                shortest_path = self._min_connect_path(centers)
+                text_comp_boxes = text_comp_boxes[shortest_path]
+                top_line = np.mean(
+                    text_comp_boxes[:, 0:2, :],
+                    axis=1).astype(np.int32).tolist()
+                bot_line = np.mean(
+                    text_comp_boxes[:, 2:4, :],
+                    axis=1).astype(np.int32).tolist()
+                top_line, bot_line = self._fix_corner(top_line, bot_line,
+                                                      text_comp_boxes[0],
+                                                      text_comp_boxes[-1])
+                boundary_points = top_line + bot_line[::-1]
+
+            else:
+                top_line = text_comp_boxes[0, 0:2, :].astype(np.int32).tolist()
+                bot_line = text_comp_boxes[0, 2:4:-1, :].astype(
+                    np.int32).tolist()
+                boundary_points = top_line + bot_line
+
+            boundary = [p for coord in boundary_points for p in coord]
+            boundaries.append(np.array(boundary, dtype=np.float32))
+            scores.append(score)
+
+        return boundaries, scores
+
+    def _norm2(self, point1: List[int], point2: List[int]) -> float:
+        """Calculate the norm of two points."""
+        return ((point1[0] - point2[0])**2 + (point1[1] - point2[1])**2)**0.5
+
+    def _min_connect_path(self, points: List[List[int]]) -> List[List[int]]:
+        """Find the shortest path to traverse all points. This code was
+        partially adapted from https://github.com/GXYM/DRRG licensed under the
+        MIT license.
+
+        Args:
+            points(List[list[int]]): The point sequence
+                [[x0, y0], [x1, y1], ...].
+
+        Returns:
+            List[list[int]]: The shortest index path.
+        """
+        assert isinstance(points, list)
+        assert all([isinstance(point, list) for point in points])
+        assert all(
+            [isinstance(coord, int) for point in points for coord in point])
+
+        points_queue = points.copy()
+        shortest_path = []
+        current_edge = [[], []]
+
+        edge_dict0 = {}
+        edge_dict1 = {}
+        current_edge[0] = points_queue[0]
+        current_edge[1] = points_queue[0]
+        points_queue.remove(points_queue[0])
+        while points_queue:
+            for point in points_queue:
+                length0 = self._norm2(point, current_edge[0])
+                edge_dict0[length0] = [point, current_edge[0]]
+                length1 = self._norm2(current_edge[1], point)
+                edge_dict1[length1] = [current_edge[1], point]
+            key0 = min(edge_dict0.keys())
+            key1 = min(edge_dict1.keys())
+
+            if key0 <= key1:
+                start = edge_dict0[key0][0]
+                end = edge_dict0[key0][1]
+                shortest_path.insert(0,
+                                     [points.index(start),
+                                      points.index(end)])
+                points_queue.remove(start)
+                current_edge[0] = start
+            else:
+                start = edge_dict1[key1][0]
+                end = edge_dict1[key1][1]
+                shortest_path.append([points.index(start), points.index(end)])
+                points_queue.remove(end)
+                current_edge[1] = end
+
+            edge_dict0 = {}
+            edge_dict1 = {}
+
+        shortest_path = functools.reduce(operator.concat, shortest_path)
+        shortest_path = sorted(set(shortest_path), key=shortest_path.index)
+
+        return shortest_path
+
+    def _in_contour(self, contour: ndarray, point: ndarray) -> bool:
+        """Whether a point is in a contour."""
+        x, y = point
+        return cv2.pointPolygonTest(contour, (int(x), int(y)), False) > 0.5
+
+    def _fix_corner(self, top_line: List[List[int]], btm_line: List[List[int]],
+                    start_box: ndarray, end_box: ndarray
+                    ) -> Tuple[List[List[int]], List[List[int]]]:
+        """Add corner points to predicted side lines. This code was partially
+        adapted from https://github.com/GXYM/DRRG licensed under the MIT
+        license.
+
+        Args:
+            top_line (List[list[int]]): The predicted top sidelines of text
+                instance.
+            btm_line (List[list[int]]): The predicted bottom sidelines of text
+                instance.
+            start_box (ndarray): The first text component box.
+            end_box (ndarray): The last text component box.
+
+        Returns:
+            tuple(top_line, bot_line):
+
+            - top_line (List[list[int]]): The top sidelines with corner point
+              added.
+            - bot_line (List[list[int]]): The bottom sidelines with corner
+              point added.
+        """
+        assert isinstance(top_line, list)
+        assert all(isinstance(point, list) for point in top_line)
+        assert isinstance(btm_line, list)
+        assert all(isinstance(point, list) for point in btm_line)
+        assert start_box.shape == end_box.shape == (4, 2)
+
+        contour = np.array(top_line + btm_line[::-1])
+        start_left_mid = (start_box[0] + start_box[3]) / 2
+        start_right_mid = (start_box[1] + start_box[2]) / 2
+        end_left_mid = (end_box[0] + end_box[3]) / 2
+        end_right_mid = (end_box[1] + end_box[2]) / 2
+        if not self._in_contour(contour, start_left_mid):
+            top_line.insert(0, start_box[0].tolist())
+            btm_line.insert(0, start_box[3].tolist())
+        elif not self._in_contour(contour, start_right_mid):
+            top_line.insert(0, start_box[1].tolist())
+            btm_line.insert(0, start_box[2].tolist())
+        if not self._in_contour(contour, end_left_mid):
+            top_line.append(end_box[0].tolist())
+            btm_line.append(end_box[3].tolist())
+        elif not self._in_contour(contour, end_right_mid):
+            top_line.append(end_box[1].tolist())
+            btm_line.append(end_box[2].tolist())
+        return top_line, btm_line
diff --git a/tests/test_models/test_textdet/test_postprocessors/test_drrg_postprocessor.py b/tests/test_models/test_textdet/test_postprocessors/test_drrg_postprocessor.py
new file mode 100644
index 00000000..90e48594
--- /dev/null
+++ b/tests/test_models/test_textdet/test_postprocessors/test_drrg_postprocessor.py
@@ -0,0 +1,29 @@
+# Copyright (c) OpenMMLab. All rights reserved.
+import unittest
+
+import numpy as np
+import torch
+from mmengine import InstanceData
+
+from mmocr.core import TextDetDataSample
+from mmocr.models.textdet.postprocessors import DRRGPostprocessor
+
+
+class TestDRRGPostProcessor(unittest.TestCase):
+
+    def test_call(self):
+
+        postprocessor = DRRGPostprocessor()
+        pred_results = (np.random.randint(0, 2, (10, 2)), np.random.rand(10),
+                        np.random.rand(2, 9))
+        data_sample = TextDetDataSample(
+            metainfo=dict(scale_factor=(0.5, 1)),
+            gt_instances=InstanceData(polygons=[
+                np.array([0, 0, 0, 1, 2, 1, 2, 0]),
+                np.array([1, 1, 1, 2, 3, 2, 3, 1])
+            ]))
+        result = postprocessor(pred_results, [data_sample])[0]
+        self.assertIn('polygons', result.pred_instances)
+        self.assertIn('scores', result.pred_instances)
+        self.assertTrue(
+            isinstance(result.pred_instances['scores'], torch.FloatTensor))