diff --git a/AssetManager.Services/PortfolioNavService.cs b/AssetManager.Services/PortfolioNavService.cs
index e8f6b95..94b0682 100644
--- a/AssetManager.Services/PortfolioNavService.cs
+++ b/AssetManager.Services/PortfolioNavService.cs
@@ -189,7 +189,9 @@ public class PortfolioNavService : IPortfolioNavService
             .ToListAsync();
 
         decimal totalCost = 0;
-        var holdingsCost = new Dictionary<string, decimal>(); // 每个标的的累计成本
+        // 每个标的的累计成本和数量（用于准确计算卖出比例）
+        var holdingsCost = new Dictionary<string, decimal>();
+        var holdingsShares = new Dictionary<string, decimal>();
         
         foreach (var tx in transactions)
         {
@@ -202,33 +204,30 @@ public class PortfolioNavService : IPortfolioNavService
                     txAmount, tx.Currency, targetCurrency);
                 totalCost += txAmountInTarget;
                 
-                // 更新该标的的累计成本
+                // 更新该标的的累计成本和数量
                 if (holdingsCost.ContainsKey(tx.StockCode))
                 {
                     holdingsCost[tx.StockCode] += txAmountInTarget;
+                    holdingsShares[tx.StockCode] += tx.Amount;
                 }
                 else
                 {
                     holdingsCost[tx.StockCode] = txAmountInTarget;
+                    holdingsShares[tx.StockCode] = tx.Amount;
                 }
             }
             else if (tx.Type == "sell")
             {
                 // 卖出时按比例减少该标的的累计成本
-                if (holdingsCost.ContainsKey(tx.StockCode) && tx.Amount > 0)
+                if (holdingsCost.ContainsKey(tx.StockCode) && holdingsShares[tx.StockCode] > 0)
                 {
-                    // 需要知道当时该标的的总数量来计算比例
-                    // 从 Position 表获取当前持仓数量（不精确，但作为近似）
-                    var position = positions.FirstOrDefault(p => p.StockCode == tx.StockCode);
-                    if (position != null && position.Shares > 0)
-                    {
-                        // 近似：用当前持仓数量 + 卖出数量 作为原来数量
-                        decimal originalShares = position.Shares + tx.Amount;
-                        decimal soldRatio = tx.Amount / originalShares;
-                        decimal costToReduce = holdingsCost[tx.StockCode] * soldRatio;
-                        holdingsCost[tx.StockCode] -= costToReduce;
-                        totalCost -= costToReduce;
-                    }
+                    decimal currentShares = holdingsShares[tx.StockCode];
+                    decimal soldRatio = tx.Amount / currentShares;
+                    decimal costToReduce = holdingsCost[tx.StockCode] * soldRatio;
+                    
+                    holdingsCost[tx.StockCode] -= costToReduce;
+                    holdingsShares[tx.StockCode] -= tx.Amount;
+                    totalCost -= costToReduce;
                 }
             }
         }
diff --git a/AssetManager.Services/PortfolioService.cs b/AssetManager.Services/PortfolioService.cs
index 9920bc7..74c928a 100755
--- a/AssetManager.Services/PortfolioService.cs
+++ b/AssetManager.Services/PortfolioService.cs
@@ -496,15 +496,17 @@ public class PortfolioService : IPortfolioService
 
             decimal positionValue = pos.Shares * CurrentPrice;
             decimal cost = pos.Shares * pos.AvgPrice;
-            decimal Profit = positionValue - cost;
-            double ProfitRate = cost > 0 ? (double)(Profit / cost * 100) : 0;
             decimal TodayProfit = previousClose > 0 ? pos.Shares * (CurrentPrice - previousClose) : 0;
 
-            // 转换为组合本位币
+            // 转换为组合本位币（先转换，再计算盈亏率，避免汇率变化影响）
             decimal positionValueInTarget = await _exchangeRateService.ConvertAmountAsync(positionValue, pos.Currency, targetCurrency);
             decimal costInTarget = await _exchangeRateService.ConvertAmountAsync(cost, pos.Currency, targetCurrency);
             decimal todayProfitInTarget = await _exchangeRateService.ConvertAmountAsync(TodayProfit, pos.Currency, targetCurrency);
 
+            // 用目标币种计算盈亏率（正确处理汇率变化）
+            decimal ProfitInTarget = positionValueInTarget - costInTarget;
+            double ProfitRate = costInTarget > 0 ? (double)(ProfitInTarget / costInTarget * 100) : 0;
+
             totalPortfolioValue += positionValueInTarget;
             totalCost += costInTarget;
             totalTodayProfit += todayProfitInTarget;