diff --git a/modules/shop/api_buy.go b/modules/shop/api_buy.go
index 878f5e912..941e3aad6 100644
--- a/modules/shop/api_buy.go
+++ b/modules/shop/api_buy.go
@@ -115,12 +115,24 @@ func (this *apiComp) Buy(session comm.IUserSession, req *pb.ShopBuyReq) (errdata
 			return
 		}
 	}
-	need = make([]*cfg.Gameatn, len(conf.Need))
-	for i, v := range conf.Need {
-		need[i] = &cfg.Gameatn{
-			A: v.A,
-			T: v.T,
-			N: int32(math.Ceil(float64(v.N)*float64(conf.Sale)/float64(1000))) * req.BuyNum,
+
+	if egood, ok := record.Preview[good.Id]; ok {
+		need = make([]*cfg.Gameatn, len(conf.Need))
+		for i, v := range egood.Need {
+			need[i] = &cfg.Gameatn{
+				A: v.A,
+				T: v.T,
+				N: v.N,
+			}
+		}
+	} else {
+		need = make([]*cfg.Gameatn, len(conf.Need))
+		for i, v := range conf.Need {
+			need[i] = &cfg.Gameatn{
+				A: v.A,
+				T: v.T,
+				N: int32(math.Ceil(float64(v.N)*float64(conf.Sale)/float64(1000))) * req.BuyNum,
+			}
 		}
 	}