diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 8a7474a..c35d285 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -76,6 +76,11 @@ jobs:
           coverage run --branch --source=mim -m pytest tests/
           coverage xml
           coverage report -m
+      - name: Run unittests with click < 8.0.0
+        run: |
+          python -m pip install click==7.1.2
+          pytest tests/
+        if: ${{matrix.python-version == '3.8'}}
       - name: Upload coverage to Codecov
         uses: codecov/codecov-action@v1.0.10
         with:
diff --git a/.gitignore b/.gitignore
index 6083fe2..59d8a7f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -144,3 +144,6 @@ data/
 *ipynb
 
 src/
+
+# vscode
+.vscode
diff --git a/mim/click/__init__.py b/mim/click/__init__.py
index fd744d2..34ed8e6 100644
--- a/mim/click/__init__.py
+++ b/mim/click/__init__.py
@@ -4,11 +4,12 @@ from .autocompletion import (
     get_installed_package,
     get_official_package,
 )
+from .compat import argument
 from .customcommand import CustomCommand
 from .option import OptionEatAll
 from .utils import param2lowercase
 
 __all__ = [
     'get_downstream_package', 'get_installed_package', 'get_official_package',
-    'OptionEatAll', 'CustomCommand', 'param2lowercase'
+    'OptionEatAll', 'CustomCommand', 'param2lowercase', 'argument'
 ]
diff --git a/mim/click/compat.py b/mim/click/compat.py
new file mode 100644
index 0000000..7d00bff
--- /dev/null
+++ b/mim/click/compat.py
@@ -0,0 +1,53 @@
+# Copyright (c) OpenMMLab. All rights reserved.
+from distutils.version import LooseVersion
+from typing import Callable
+
+import click
+
+
+def autocompletion_to_shell_complete(autocompletion: Callable) -> Callable:
+    """Convert autocompletion to shell_complete.
+
+    Reference:
+    https://github.com/pallets/click/blob/8.0.0/src/click/core.py#L2059
+
+    Args:
+        autocompletion (callable): A function that returns custom shell
+            completions. Takes ``ctx, param, incomplete`` and must return a
+            list of string.
+
+    Returns:
+        A shell_complete function converted from autocompletion.
+    """
+
+    def shell_complete(ctx, param, incomplete):
+        from click.shell_completion import CompletionItem
+
+        out = []
+        for c in autocompletion(ctx, [], incomplete):
+            if isinstance(c, tuple):
+                c = CompletionItem(c[0], help=c[1])
+            elif isinstance(c, str):
+                c = CompletionItem(c)
+
+            if c.value.startswith(incomplete):
+                out.append(c)
+        return out
+
+    return shell_complete
+
+
+def argument(*param_decls, **attrs):
+    """A decorator compatible with click 7.x and 8.x.
+
+    Same as ``click.argument``.
+    """
+    # 'autocompletion' will be removed in Click 8.1 and its new name is
+    # 'shell_complete'.
+    if LooseVersion(click.__version__) >= LooseVersion('8.0.0'):
+        autocompletion = attrs.pop('autocompletion', None)
+        if autocompletion is not None:
+            attrs['shell_complete'] = autocompletion_to_shell_complete(
+                autocompletion)
+
+    return click.argument(*param_decls, **attrs)
diff --git a/mim/click/option.py b/mim/click/option.py
index 5e58322..ec2b068 100644
--- a/mim/click/option.py
+++ b/mim/click/option.py
@@ -45,3 +45,15 @@ class OptionEatAll(click.Option):
                 our_parser.process = parser_process
                 break
         return retval
+
+    def type_cast_value(self, ctx, value):
+        """Convert and validate a value against the option's
+        :attr:`type`, :attr:`multiple`, and :attr:`nargs`.
+
+        Since the :attr:`type` of OptionEatAll is `STRING`, override the
+        `type_cast_value` method to prevent the return value of OptionEatAll
+        converted from a tuple to a string.
+        """
+        if value is None:
+            return () if self.multiple or self.nargs == -1 else None
+        return tuple(self.type(x, self, ctx) for x in value)
diff --git a/mim/commands/download.py b/mim/commands/download.py
index 1e42ac0..0a9ea1f 100644
--- a/mim/commands/download.py
+++ b/mim/commands/download.py
@@ -4,7 +4,12 @@ from typing import List, Optional
 
 import click
 
-from mim.click import OptionEatAll, get_downstream_package, param2lowercase
+from mim.click import (
+    OptionEatAll,
+    argument,
+    get_downstream_package,
+    param2lowercase,
+)
 from mim.commands.search import get_model_info
 from mim.utils import (
     DEFAULT_CACHE_DIR,
@@ -18,7 +23,7 @@ from mim.utils import (
 
 
 @click.command('download')
-@click.argument(
+@argument(
     'package',
     type=str,
     autocompletion=get_downstream_package,
diff --git a/mim/commands/install.py b/mim/commands/install.py
index 6ffe40b..92bb980 100644
--- a/mim/commands/install.py
+++ b/mim/commands/install.py
@@ -10,7 +10,7 @@ from typing import List
 import click
 import pip
 
-from mim.click import get_official_package, param2lowercase
+from mim.click import argument, get_official_package, param2lowercase
 from mim.commands.uninstall import uninstall
 from mim.utils import (
     DEFAULT_URL,
@@ -35,7 +35,7 @@ from mim.utils import (
 
 
 @click.command('install')
-@click.argument(
+@argument(
     'package',
     type=str,
     autocompletion=get_official_package,
diff --git a/mim/commands/search.py b/mim/commands/search.py
index 155b0e5..b20eae4 100644
--- a/mim/commands/search.py
+++ b/mim/commands/search.py
@@ -12,7 +12,12 @@ from modelindex.load_model_index import load
 from modelindex.models.ModelIndex import ModelIndex
 from pandas import DataFrame, Series
 
-from mim.click import OptionEatAll, get_downstream_package, param2lowercase
+from mim.click import (
+    OptionEatAll,
+    argument,
+    get_downstream_package,
+    param2lowercase,
+)
 from mim.utils import (
     DEFAULT_CACHE_DIR,
     PKG2PROJECT,
@@ -27,7 +32,7 @@ from mim.utils import (
 
 
 @click.command('search')
-@click.argument(
+@argument(
     'packages',
     nargs=-1,
     type=click.STRING,
diff --git a/mim/commands/uninstall.py b/mim/commands/uninstall.py
index 5649df4..cb99355 100644
--- a/mim/commands/uninstall.py
+++ b/mim/commands/uninstall.py
@@ -1,12 +1,12 @@
 # Copyright (c) OpenMMLab. All rights reserved.
 import click
 
-from mim.click import get_installed_package, param2lowercase
+from mim.click import argument, get_installed_package, param2lowercase
 from mim.utils import call_command
 
 
 @click.command('uninstall')
-@click.argument(
+@argument(
     'package', autocompletion=get_installed_package, callback=param2lowercase)
 @click.option(
     '-y',
diff --git a/requirements/install.txt b/requirements/install.txt
index f50d783..96a0867 100644
--- a/requirements/install.txt
+++ b/requirements/install.txt
@@ -1,4 +1,4 @@
-Click==7.1.2
+Click
 colorama
 model-index
 pandas
diff --git a/setup.py b/setup.py
index 8d082fe..070dfae 100644
--- a/setup.py
+++ b/setup.py
@@ -29,7 +29,7 @@ setup(
     include_package_data=True,
     python_requires='>=3.6',
     install_requires=[
-        'Click==7.1.2',
+        'Click',
         'colorama',
         'requests',
         'model-index',
diff --git a/tests/test_search.py b/tests/test_search.py
index 5354243..c41e2ea 100644
--- a/tests/test_search.py
+++ b/tests/test_search.py
@@ -103,6 +103,10 @@ def test_search():
     result = runner.invoke(search, ['mmcls', '--sort', 'epochs'])
     assert result.exit_code == 0
 
+    # mim search mmcls --sort batch_size epochs
+    result = runner.invoke(search, ['mmcls', '--sort', 'batch_size', 'epochs'])
+    assert result.exit_code == 0
+
     # mim search mmcls --field epoch
     result = runner.invoke(search, ['mmcls', '--field', 'epoch'])
     assert result.exit_code == 0