diff --git a/nanobot/channels/dingtalk.py b/nanobot/channels/dingtalk.py
index 8d02fa6..8e2a2be 100644
--- a/nanobot/channels/dingtalk.py
+++ b/nanobot/channels/dingtalk.py
@@ -70,6 +70,13 @@ class NanobotDingTalkHandler(CallbackHandler):
             sender_id = chatbot_msg.sender_staff_id or chatbot_msg.sender_id
             sender_name = chatbot_msg.sender_nick or "Unknown"
 
+            # Extract conversation info
+            conversation_type = message.data.get("conversationType")
+            conversation_id = message.data.get("conversationId") or message.data.get("openConversationId")
+
+            if conversation_type == "2" and conversation_id:
+                sender_id = f"group:{conversation_id}"
+
             logger.info("Received DingTalk message from {} ({}): {}", sender_name, sender_id, content)
 
             # Forward to Nanobot via _on_message (non-blocking).
@@ -301,14 +308,25 @@ 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": "sampleMarkdown",
+                "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)