diff --git a/backend/app/services/paper_trading_service.py b/backend/app/services/paper_trading_service.py
index b3c82a7..6fa9c2c 100644
--- a/backend/app/services/paper_trading_service.py
+++ b/backend/app/services/paper_trading_service.py
@@ -245,8 +245,8 @@ class PaperTradingService:
         if quantity_from_signal is not None and quantity_from_signal > 0:
             # LLM 决策的 quantity 是保证金金额
             margin = float(quantity_from_signal)
-            # 计算持仓价值（保证金 × 杠杆）
-            position_value = margin * self.leverage
+            # 计算持仓价值（保证金 × 杠杆），保留2位小数
+            position_value = round(margin * self.leverage, 2)
             logger.debug(f"使用 LLM 决策保证金: ${margin:.2f}, 持仓价值: ${position_value:.2f}")
         else:
             # 回退到动态仓位计算
@@ -259,7 +259,7 @@ class PaperTradingService:
             result['message'] = msg
             return result
 
-        quantity = position_value  # 订单数量（以 USDT 计价）
+        quantity = round(position_value, 2)  # 确保持仓价值保留2位小数
 
         # 确定入场类型
         entry_type_str = signal.get('entry_type', 'market')