diff --git a/backend/live_executor.py b/backend/live_executor.py
index 1ca2975..6f4f70e 100644
--- a/backend/live_executor.py
+++ b/backend/live_executor.py
@@ -206,14 +206,21 @@ async def place_stop_order(session: aiohttp.ClientSession, symbol: str, side: st
         "reduceOnly": "true",
     }
 
-    # 测试网不支持STOP_MARKET/TAKE_PROFIT_MARKET，降级为STOP/TAKE_PROFIT（限价单）
-    if TRADE_ENV == "testnet" and order_type in ("STOP_MARKET", "TAKE_PROFIT_MARKET"):
-        fallback_type = "STOP" if "STOP" in order_type else "TAKE_PROFIT"
-        params["type"] = fallback_type
-        params["price"] = price_str  # 限价单需要price
-        params["timeInForce"] = "GTC"
-
+    # 先尝试传统endpoint
     data, status = await binance_request(session, "POST", "/fapi/v1/order", params)
+
+    # 如果不支持(-4120)，降级到Algo Order API
+    if status == 400 and isinstance(data, dict) and data.get("code") == -4120:
+        logger.info(f"[{symbol}] 传统endpoint不支持{order_type}，切换Algo Order API")
+        algo_params = {
+            "symbol": symbol,
+            "side": side,
+            "type": order_type,
+            "stopPrice": price_str,
+            "quantity": qty_str,
+            "reduceOnly": "true",
+        }
+        data, status = await binance_request(session, "POST", "/fapi/v1/algo/order", algo_params)
     if status == 200:
         logger.info(f"[{symbol}] 📌 挂{order_type} {side} @ {price_str} qty={qty_str} | orderId={data.get('orderId')}")
     return data, status