diff --git a/gateway/platforms/feishu.py b/gateway/platforms/feishu.py
index a88c7e52b937..5dd920c3f9b2 100644
--- a/gateway/platforms/feishu.py
+++ b/gateway/platforms/feishu.py
@@ -3249,7 +3249,14 @@ async def _send_raw_message(
             content=payload,
             uuid_value=str(uuid.uuid4()),
         )
-        request = self._build_create_message_request("chat_id", body)
+        # Infer receive_id_type from the ID prefix
+        if chat_id.startswith("ou_"):
+            rid_type = "open_id"
+        elif chat_id.startswith("on_"):
+            rid_type = "union_id"
+        else:
+            rid_type = "chat_id"
+        request = self._build_create_message_request(rid_type, body)
         return await asyncio.to_thread(self._client.im.v1.message.create, request)
 
     @staticmethod
diff --git a/tests/gateway/test_feishu.py b/tests/gateway/test_feishu.py
index 47f274d1b7e4..2088f41225c2 100644
--- a/tests/gateway/test_feishu.py
+++ b/tests/gateway/test_feishu.py
@@ -2009,6 +2009,49 @@ async def _sleep(delay):
         self.assertEqual(captured["attempts"], 1)
         self.assertEqual(sleeps, [])
 
+    @patch.dict(os.environ, {}, clear=True)
+    def test_send_infers_receive_id_type_from_id_prefix(self):
+        from gateway.config import PlatformConfig
+        from gateway.platforms.feishu import FeishuAdapter
+
+        adapter = FeishuAdapter(PlatformConfig())
+
+        cases = [
+            ("oc_group_chat", "chat_id"),
+            ("ou_user_open_id", "open_id"),
+            ("on_union_id", "union_id"),
+        ]
+
+        for chat_id, expected_type in cases:
+            captured = {}
+
+            class _MessageAPI:
+                def create(self, request):
+                    captured["request"] = request
+                    return SimpleNamespace(
+                        success=lambda: True,
+                        data=SimpleNamespace(message_id="om_test"),
+                    )
+
+            adapter._client = SimpleNamespace(
+                im=SimpleNamespace(
+                    v1=SimpleNamespace(
+                        message=_MessageAPI(),
+                    )
+                )
+            )
+
+            async def _direct(func, *args, **kwargs):
+                return func(*args, **kwargs)
+
+            with patch("gateway.platforms.feishu.asyncio.to_thread", side_effect=_direct):
+                asyncio.run(adapter.send(chat_id=chat_id, content="test"))
+
+            self.assertEqual(
+                captured["request"].receive_id_type, expected_type,
+                f"chat_id={chat_id!r} should use receive_id_type={expected_type!r}",
+            )
+
     @patch.dict(os.environ, {}, clear=True)
     def test_send_document_reply_uses_thread_flag(self):
         from gateway.config import PlatformConfig