diff --git a/src/core/app_state.py b/src/core/app_state.py
index b390f56..f755a9f 100644
--- a/src/core/app_state.py
+++ b/src/core/app_state.py
@@ -94,19 +94,10 @@ def login() -> bool:
     global _trader_instance
     
     try:
-        if _trader_instance is not None and is_real_mode():
-            # _trader_instance is BaseTrader or its child, which should have logout
-            _trader_instance.logout() 
-            _trader_instance = None
-            
+        logout() 
         _trader_instance = SimulationTrader() if Config.SIMULATION_MODE else XtTrader(connect_failed_callback=on_connect_failed)
         
         logger.info("开始登录")
-        
-        if Config.SIMULATION_MODE:
-            return True
-            
-        # _trader_instance is XtTrader here, which has login
         login_success = _trader_instance.login() 
         
         if login_success:
@@ -117,7 +108,7 @@ def login() -> bool:
                 return True
             else:
                 logger.error(f"登录成功但查询余额失败: {result}")
-                if _trader_instance:
+                if _trader_instance and is_real_mode():
                     _trader_instance.connection_failed = True # BaseTrader property
                     _trader_instance.last_reconnect_time = time.time() # BaseTrader property
                     _trader_instance.notify_connection_failure("登录成功但查询余额失败") # BaseTrader method
@@ -127,7 +118,7 @@ def login() -> bool:
             return False
     except Exception as e:
         logger.error(f"登录初始化异常: {str(e)}")
-        if is_real_mode() and _trader_instance is not None:
+        if _trader_instance and is_real_mode():
             _trader_instance.connection_failed = True
             _trader_instance.last_reconnect_time = time.time()
             _trader_instance.notify_connection_failure(f"登录初始化异常: {str(e)}")
@@ -139,7 +130,7 @@ def logout() -> None:
     """登出并销毁交易实例。"""
     global _trader_instance
     
-    if _trader_instance is not None:
+    if _trader_instance:
         _trader_instance.logout()
         logger.info("登出成功")