diff --git a/nanobot/channels/dingtalk.py b/nanobot/channels/dingtalk.py
index 72199fdf9..4be3ccb97 100644
--- a/nanobot/channels/dingtalk.py
+++ b/nanobot/channels/dingtalk.py
@@ -160,6 +160,7 @@ class DingTalkConfig(Base):
     allow_from: list[str] = Field(default_factory=list)
     allow_remote_media_redirects: bool = False
     remote_media_redirect_allowed_hosts: list[str] = Field(default_factory=list)
+    group_user_isolation: bool = False  # If True, each user in group chat gets their own session
 
 
 class DingTalkChannel(BaseChannel):
@@ -693,6 +694,9 @@ class DingTalkChannel(BaseChannel):
             self.logger.info("inbound: {} from {}", content, sender_name)
             is_group = conversation_type == "2" and conversation_id
             chat_id = f"group:{conversation_id}" if is_group else sender_id
+            session_key = None
+            if is_group and self.config.group_user_isolation:
+                session_key = f"{self.name}:group:{conversation_id}:{sender_id}"
             await self._handle_message(
                 sender_id=sender_id,
                 chat_id=chat_id,
@@ -702,6 +706,7 @@ class DingTalkChannel(BaseChannel):
                     "platform": "dingtalk",
                     "conversation_type": conversation_type,
                 },
+                session_key=session_key,
             )
         except Exception:
             self.logger.exception("Error publishing message")
diff --git a/tests/channels/test_dingtalk_channel.py b/tests/channels/test_dingtalk_channel.py
index f14c81302..d36759431 100644
--- a/tests/channels/test_dingtalk_channel.py
+++ b/tests/channels/test_dingtalk_channel.py
@@ -98,6 +98,55 @@ async def test_group_message_keeps_sender_id_and_routes_chat_id() -> None:
     assert msg.metadata["conversation_type"] == "2"
 
 
+@pytest.mark.asyncio
+async def test_group_user_isolation_false_uses_shared_session() -> None:
+    """By default group messages share the same session_key."""
+    config = DingTalkConfig(
+        client_id="app", client_secret="secret", allow_from=["*"], group_user_isolation=False
+    )
+    bus = MessageBus()
+    channel = DingTalkChannel(config, bus)
+
+    for user_id in ("user1", "user2"):
+        await channel._on_message(
+            "hello",
+            sender_id=user_id,
+            sender_name=user_id,
+            conversation_type="2",
+            conversation_id="conv123",
+        )
+
+    msg1 = await bus.consume_inbound()
+    msg2 = await bus.consume_inbound()
+    assert msg1.session_key == msg2.session_key == "dingtalk:group:conv123"
+    assert msg1.chat_id == msg2.chat_id == "group:conv123"
+
+
+@pytest.mark.asyncio
+async def test_group_user_isolation_true_separates_sessions() -> None:
+    """When group_user_isolation is True, each user gets their own session_key."""
+    config = DingTalkConfig(
+        client_id="app", client_secret="secret", allow_from=["*"], group_user_isolation=True
+    )
+    bus = MessageBus()
+    channel = DingTalkChannel(config, bus)
+
+    for user_id in ("user1", "user2"):
+        await channel._on_message(
+            "hello",
+            sender_id=user_id,
+            sender_name=user_id,
+            conversation_type="2",
+            conversation_id="conv123",
+        )
+
+    msg1 = await bus.consume_inbound()
+    msg2 = await bus.consume_inbound()
+    assert msg1.session_key == "dingtalk:group:conv123:user1"
+    assert msg2.session_key == "dingtalk:group:conv123:user2"
+    assert msg1.chat_id == msg2.chat_id == "group:conv123"
+
+
 @pytest.mark.asyncio
 async def test_group_send_uses_group_messages_api() -> None:
     config = DingTalkConfig(client_id="app", client_secret="secret", allow_from=["*"])