diff --git a/src/containerapp-preview/HISTORY.rst b/src/containerapp-preview/HISTORY.rst
index feb2781d99b..00c5aa4cc3d 100644
--- a/src/containerapp-preview/HISTORY.rst
+++ b/src/containerapp-preview/HISTORY.rst
@@ -5,7 +5,7 @@ Release History
 upcoming
 ++++++
 * containerapp-preview requires the version of containerapp extension >= 0.3.36
-
+* containerapp-preview auto install containerapp extension if not exist
 
 1.0.0b1
 ++++++
diff --git a/src/containerapp-preview/azext_containerapp_preview/__init__.py b/src/containerapp-preview/azext_containerapp_preview/__init__.py
index c3da75d3d51..88d2075256e 100644
--- a/src/containerapp-preview/azext_containerapp_preview/__init__.py
+++ b/src/containerapp-preview/azext_containerapp_preview/__init__.py
@@ -6,7 +6,7 @@
 from azure.cli.core import AzCommandsLoader
 
 from azext_containerapp_preview._help import helps  # pylint: disable=unused-import
-from azext_containerapp_preview._utils import (_get_azext_containerapp_module)
+from azext_containerapp_preview._utils import (_get_azext_containerapp_module, auto_install_containerapp_extension_if_not_exist)
 
 
 class ContainerappPreviewCommandsLoader(AzCommandsLoader):
@@ -18,6 +18,7 @@ def __init__(self, cli_ctx=None):
             client_factory=None)
         super(ContainerappPreviewCommandsLoader, self).__init__(cli_ctx=cli_ctx,
                                                                 custom_command_type=containerapp_preview_custom)
+        auto_install_containerapp_extension_if_not_exist(self)
 
     def load_command_table(self, args):
         from azext_containerapp_preview.commands import load_command_table
diff --git a/src/containerapp-preview/azext_containerapp_preview/_utils.py b/src/containerapp-preview/azext_containerapp_preview/_utils.py
index f99953bc1ce..32f00133d8d 100644
--- a/src/containerapp-preview/azext_containerapp_preview/_utils.py
+++ b/src/containerapp-preview/azext_containerapp_preview/_utils.py
@@ -4,7 +4,7 @@
 # --------------------------------------------------------------------------------------------
 # pylint: disable=line-too-long
 
-from azure.cli.core.azclierror import NoTTYError, ValidationError
+from azure.cli.core.azclierror import ValidationError
 from knack.util import CLIError
 from knack.log import get_logger
 
@@ -38,6 +38,28 @@ def _get_azext_containerapp_module(module_name):
         # Import the extension module
         from importlib import import_module
         azext_custom = import_module(module_name)
+
+        # need to reload preview's _help, because the containerapp's _help will overwrite the preview's _help after importing the containerapp module.
+        from azext_containerapp_preview import _help
+        from importlib import reload
+        reload(_help)
+
         return azext_custom
     except ImportError as ie:
         raise CLIError(ie) from ie
+
+
+def auto_install_containerapp_extension_if_not_exist(cmd):
+    from azure.cli.core.extension import extension_exists
+
+    if not extension_exists(GA_CONTAINERAPP_EXTENSION_NAME):
+        _install_containerapp_extension(cmd, GA_CONTAINERAPP_EXTENSION_NAME)
+
+
+def _install_containerapp_extension(cmd, extension_name, upgrade=False):
+    try:
+        from azure.cli.core.extension import operations
+        operations.add_extension(cmd=cmd, extension_name=extension_name, upgrade=upgrade)
+    except Exception:  # nopa pylint: disable=broad-except
+        return False
+    return True