diff --git a/internal/service/order/service.go b/internal/service/order/service.go
index bda54e3..02a3a7f 100644
--- a/internal/service/order/service.go
+++ b/internal/service/order/service.go
@@ -259,7 +259,9 @@ func (s *Service) CreateLegacy(ctx context.Context, req *dto.CreateOrderRequest,
 			operatorType = "agent"
 			actualPaidAmount = &operatorCostPrice
 			purchaseRole = model.PurchaseRolePurchaseForSubordinate
-			sellerCostPrice = buyerCostPrice
+			// 代理代购下级时，佣金差额基准应是操作方（代理自己）的成本价，而非下级的成本价
+			// 使用 buyerCostPrice 会导致差额为 0，上级代理无法获得应有佣金
+			sellerCostPrice = operatorCostPrice
 		}
 	}
 
@@ -545,7 +547,8 @@ func (s *Service) CreateAdminOrder(ctx context.Context, req *dto.CreateAdminOrde
 			operatorType = "agent"
 			actualPaidAmount = &operatorCostPrice
 			purchaseRole = model.PurchaseRolePurchaseForSubordinate
-			sellerCostPrice = buyerCostPrice
+			// 代理代购下级时，佣金差额基准应是操作方（代理自己）的成本价，而非下级的成本价
+			sellerCostPrice = operatorCostPrice
 		}
 	} else {
 		// 兜底检查：后台不支持其他支付方式（DTO 验证已拒绝，此为防御性编程）
@@ -806,7 +809,8 @@ func (s *Service) CreateH5Order(ctx context.Context, req *dto.CreateOrderRequest
 			operatorType = "agent"
 			actualPaidAmount = &operatorCostPrice
 			purchaseRole = model.PurchaseRolePurchaseForSubordinate
-			sellerCostPrice = buyerCostPrice
+			// 代理代购下级时，佣金差额基准应是操作方（代理自己）的成本价，而非下级的成本价
+			sellerCostPrice = operatorCostPrice
 		}
 	}