diff --git a/nanobot/channels/dingtalk.py b/nanobot/channels/dingtalk.py
index 8d02fa6..3c301a9 100644
--- a/nanobot/channels/dingtalk.py
+++ b/nanobot/channels/dingtalk.py
@@ -70,12 +70,24 @@ class NanobotDingTalkHandler(CallbackHandler):
             sender_id = chatbot_msg.sender_staff_id or chatbot_msg.sender_id
             sender_name = chatbot_msg.sender_nick or "Unknown"
 
+            conversation_type = message.data.get("conversationType")
+            conversation_id = (
+                message.data.get("conversationId")
+                or message.data.get("openConversationId")
+            )
+
             logger.info("Received DingTalk message from {} ({}): {}", sender_name, sender_id, content)
 
             # Forward to Nanobot via _on_message (non-blocking).
             # Store reference to prevent GC before task completes.
             task = asyncio.create_task(
-                self.channel._on_message(content, sender_id, sender_name)
+                self.channel._on_message(
+                    content,
+                    sender_id,
+                    sender_name,
+                    conversation_type,
+                    conversation_id,
+                )
             )
             self.channel._background_tasks.add(task)
             task.add_done_callback(self.channel._background_tasks.discard)
@@ -95,8 +107,8 @@ class DingTalkChannel(BaseChannel):
     Uses WebSocket to receive events via `dingtalk-stream` SDK.
     Uses direct HTTP API to send messages (SDK is mainly for receiving).
 
-    Note: Currently only supports private (1:1) chat. Group messages are
-    received but replies are sent back as private messages to the sender.
+    Supports both private (1:1) and group chats.
+    Group chat_id is stored with a "group:" prefix to route replies back.
     """
 
     name = "dingtalk"
@@ -301,14 +313,25 @@ class DingTalkChannel(BaseChannel):
             logger.warning("DingTalk HTTP client not initialized, cannot send")
             return False
 
-        url = "https://api.dingtalk.com/v1.0/robot/oToMessages/batchSend"
         headers = {"x-acs-dingtalk-access-token": token}
-        payload = {
-            "robotCode": self.config.client_id,
-            "userIds": [chat_id],
-            "msgKey": msg_key,
-            "msgParam": json.dumps(msg_param, ensure_ascii=False),
-        }
+        if chat_id.startswith("group:"):
+            # Group chat
+            url = "https://api.dingtalk.com/v1.0/robot/groupMessages/send"
+            payload = {
+                "robotCode": self.config.client_id,
+                "openConversationId": chat_id[6:],  # Remove "group:" prefix,
+                "msgKey": msg_key,
+                "msgParam": json.dumps(msg_param, ensure_ascii=False),
+            }
+        else:
+            # Private chat
+            url = "https://api.dingtalk.com/v1.0/robot/oToMessages/batchSend"
+            payload = {
+                "robotCode": self.config.client_id,
+                "userIds": [chat_id],
+                "msgKey": msg_key,
+                "msgParam": json.dumps(msg_param, ensure_ascii=False),
+            }
 
         try:
             resp = await self._http.post(url, json=payload, headers=headers)
@@ -417,7 +440,14 @@ class DingTalkChannel(BaseChannel):
                 f"[Attachment send failed: {filename}]",
             )
 
-    async def _on_message(self, content: str, sender_id: str, sender_name: str) -> None:
+    async def _on_message(
+        self,
+        content: str,
+        sender_id: str,
+        sender_name: str,
+        conversation_type: str | None = None,
+        conversation_id: str | None = None,
+    ) -> None:
         """Handle incoming message (called by NanobotDingTalkHandler).
 
         Delegates to BaseChannel._handle_message() which enforces allow_from
@@ -425,13 +455,16 @@ class DingTalkChannel(BaseChannel):
         """
         try:
             logger.info("DingTalk 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
             await self._handle_message(
                 sender_id=sender_id,
-                chat_id=sender_id,  # For private chat, chat_id == sender_id
+                chat_id=chat_id,
                 content=str(content),
                 metadata={
                     "sender_name": sender_name,
                     "platform": "dingtalk",
+                    "conversation_type": conversation_type,
                 },
             )
         except Exception as e:
diff --git a/tests/test_dingtalk_channel.py b/tests/test_dingtalk_channel.py
new file mode 100644
index 0000000..7595a33
--- /dev/null
+++ b/tests/test_dingtalk_channel.py
@@ -0,0 +1,66 @@
+from types import SimpleNamespace
+
+import pytest
+
+from nanobot.bus.queue import MessageBus
+from nanobot.channels.dingtalk import DingTalkChannel
+from nanobot.config.schema import DingTalkConfig
+
+
+class _FakeResponse:
+    def __init__(self, status_code: int = 200, json_body: dict | None = None) -> None:
+        self.status_code = status_code
+        self._json_body = json_body or {}
+        self.text = "{}"
+
+    def json(self) -> dict:
+        return self._json_body
+
+
+class _FakeHttp:
+    def __init__(self) -> None:
+        self.calls: list[dict] = []
+
+    async def post(self, url: str, json=None, headers=None):
+        self.calls.append({"url": url, "json": json, "headers": headers})
+        return _FakeResponse()
+
+
+@pytest.mark.asyncio
+async def test_group_message_keeps_sender_id_and_routes_chat_id() -> None:
+    config = DingTalkConfig(client_id="app", client_secret="secret", allow_from=["user1"])
+    bus = MessageBus()
+    channel = DingTalkChannel(config, bus)
+
+    await channel._on_message(
+        "hello",
+        sender_id="user1",
+        sender_name="Alice",
+        conversation_type="2",
+        conversation_id="conv123",
+    )
+
+    msg = await bus.consume_inbound()
+    assert msg.sender_id == "user1"
+    assert msg.chat_id == "group:conv123"
+    assert msg.metadata["conversation_type"] == "2"
+
+
+@pytest.mark.asyncio
+async def test_group_send_uses_group_messages_api() -> None:
+    config = DingTalkConfig(client_id="app", client_secret="secret", allow_from=["*"])
+    channel = DingTalkChannel(config, MessageBus())
+    channel._http = _FakeHttp()
+
+    ok = await channel._send_batch_message(
+        "token",
+        "group:conv123",
+        "sampleMarkdown",
+        {"text": "hello", "title": "Nanobot Reply"},
+    )
+
+    assert ok is True
+    call = channel._http.calls[0]
+    assert call["url"] == "https://api.dingtalk.com/v1.0/robot/groupMessages/send"
+    assert call["json"]["openConversationId"] == "conv123"
+    assert call["json"]["msgKey"] == "sampleMarkdown"