diff --git a/backend/internal/service/provider_dlc.go b/backend/internal/service/provider_dlc.go
index 2c762c8..399b718 100644
--- a/backend/internal/service/provider_dlc.go
+++ b/backend/internal/service/provider_dlc.go
@@ -220,9 +220,10 @@ func (p *DLCProvider) Submit(ctx context.Context, order *model.FulfillmentOrder,
 	partial := map[string]interface{}{
 		"provider": ProviderDLC,
 	}
-	effectiveOrderSN := order.OrderNo
-	if savedSN := resultDataString(order.ResultData, "order_sn"); savedSN != "" {
-		effectiveOrderSN = savedSN
+	// 代练仓下正式单前会按这个单号回查。随机后缀在库里不存在，不能再拿去下单。
+	effectiveOrderSN := strings.TrimSpace(order.OrderNo)
+	if savedSN := resultDataString(order.ResultData, "order_sn"); savedSN != "" && savedSN != effectiveOrderSN {
+		queueOrderID = ""
 	}
 
 	if queueOrderID == "" {
@@ -263,29 +264,7 @@ func (p *DLCProvider) Submit(ctx context.Context, order *model.FulfillmentOrder,
 
 	upstreamOrder, err := p.createUpstreamOrder(queueOrderID, gameAccount, goodID, effectiveOrderSN)
 	if err != nil {
-		if isQueueDeadError(err) {
-			// 创建正式单阶段出现订单不可操作或重复提交，尝试换新重试单号重建队列重试一次
-			delete(partial, "queue_order_id")
-			retryBaseSN := fmt.Sprintf("%s_%x", strings.SplitN(order.OrderNo, "_", 2)[0], time.Now().UnixNano()%0xffff)
-			newQueueID, newSN, createErr := p.createOrderQueue(goodID, retryBaseSN, goodsNo)
-			if createErr == nil {
-				queueOrderID = newQueueID
-				effectiveOrderSN = newSN
-				partial["queue_order_id"] = queueOrderID
-				partial["order_sn"] = effectiveOrderSN
-				if patchErr := p.patchOrderQueue(queueOrderID, gameAccount, bindUUID, goodsNo, goodsName); patchErr == nil {
-					if retriedOrder, retriedErr := p.createUpstreamOrder(queueOrderID, gameAccount, goodID, effectiveOrderSN); retriedErr == nil {
-						upstreamOrder = retriedOrder
-						err = nil
-					} else {
-						err = retriedErr
-					}
-				}
-			}
-		}
-		if err != nil {
-			return &ProviderSubmitResult{PatchResultData: partial}, fmt.Errorf("创建上游正式订单失败: %w", err)
-		}
+		return &ProviderSubmitResult{PatchResultData: partial}, fmt.Errorf("创建上游正式订单失败: %w", err)
 	}
 
 	providerOrderNo := firstNonEmpty(
@@ -398,43 +377,28 @@ func (p *DLCProvider) createOrderQueue(goodID, orderNo, goodsNo string) (string,
 	var out struct {
 		Orders []map[string]interface{} `json:"orders"`
 	}
-	usedSN := orderNo
+	orderNo = strings.TrimSpace(orderNo)
 	payload := map[string]interface{}{
 		"good_id":   goodID,
 		"quantity":  1,
-		"order_sn":  usedSN,
+		"order_sn":  orderNo,
 		"h5_prefix": p.channel,
 	}
 	if goodsNo != "" {
 		payload["goods_no"] = goodsNo
 	}
-	err := p.signProxy("/public/users/orders-queue", "POST", payload, &out)
-	if err != nil {
-		if strings.Contains(err.Error(), "正在处理中") ||
-			strings.Contains(err.Error(), "请勿重复提交") ||
-			strings.Contains(err.Error(), "已有发货记录") ||
-			strings.Contains(err.Error(), "已处理") {
-			// DLC 已存在此 order_sn 的队列/发货记录，追加随机后缀重新创建队列
-			retrySN := fmt.Sprintf("%s_%x", strings.SplitN(orderNo, "_", 2)[0], time.Now().UnixNano()%0xffff)
-			usedSN = retrySN
-			payload["order_sn"] = usedSN
-			out.Orders = nil
-			if retryErr := p.signProxy("/public/users/orders-queue", "POST", payload, &out); retryErr == nil && len(out.Orders) > 0 {
-				err = nil
-			}
-		}
-	}
-	if err != nil {
-		return "", "", err
+	// 代练仓已有这条单号时，原文是「请续发未完成项或重试失败项」。换一个带后缀的单号会让回查 404。
+	if err := p.signProxy("/public/users/orders-queue", "POST", payload, &out); err != nil {
+		return "", orderNo, err
 	}
 	if len(out.Orders) == 0 {
-		return "", "", errors.New("发货服务未返回队列订单")
+		return "", orderNo, errors.New("发货服务未返回队列订单")
 	}
 	orderID := firstNonEmpty(stringFromMap(out.Orders[0], "_id"), stringFromMap(out.Orders[0], "id"))
 	if orderID == "" {
-		return "", "", errors.New("发货服务未返回队列订单 ID")
+		return "", orderNo, errors.New("发货服务未返回队列订单 ID")
 	}
-	return orderID, usedSN, nil
+	return orderID, orderNo, nil
 }
 
 func (p *DLCProvider) patchOrderQueue(orderID, gameAccount, bindUUID, goodsNo, goodsName string) error {
@@ -632,4 +596,3 @@ func (p *DLCProvider) signProxy(path, method string, data interface{}, out inter
 
 	return lastErr
 }
-
diff --git a/backend/internal/service/provider_dlc_test.go b/backend/internal/service/provider_dlc_test.go
index b9bfc1f..71ba537 100644
--- a/backend/internal/service/provider_dlc_test.go
+++ b/backend/internal/service/provider_dlc_test.go
@@ -5,6 +5,7 @@ import (
 	"errors"
 	"net/http"
 	"net/http/httptest"
+	"strings"
 	"sync/atomic"
 	"testing"
 	"time"
@@ -179,6 +180,39 @@ func TestSignProxyDoesNotRetryOnRateLimit(t *testing.T) {
 	}
 }
 
+func TestDLCCreateOrderQueueKeepsOriginalOrderSN(t *testing.T) {
+	const orderNo = "FO20261006180010b19fbe66ec3"
+	var requestedSN string
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		var body struct {
+			Path string                 `json:"path"`
+			Data map[string]interface{} `json:"data"`
+		}
+		_ = json.NewDecoder(r.Body).Decode(&body)
+		requestedSN, _ = body.Data["order_sn"].(string)
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(http.StatusBadRequest)
+		_ = json.NewEncoder(w).Encode(map[string]interface{}{
+			"code":    1,
+			"message": "该订单已有发货记录，请续发未完成项或重试失败项",
+		})
+	}))
+	defer server.Close()
+
+	p := NewDLCProvider(server.URL, "dlc", &http.Client{Timeout: 5 * time.Second})
+	_, sn, err := p.createOrderQueue("good-1", orderNo, "suit_romantic_destiny")
+	if err == nil {
+		t.Fatal("已有发货记录时应返回代练仓原文，不能换成新单号重试")
+	}
+	if !strings.Contains(err.Error(), "请续发未完成项或重试失败项") {
+		t.Fatalf("应保留代练仓原文，实际: %v", err)
+	}
+	if requestedSN != orderNo || sn != orderNo || strings.Contains(requestedSN, "_") {
+		t.Fatalf("请求单号被改写: requested=%s returned=%s", requestedSN, sn)
+	}
+}
+
 func TestSignProxyDoesNotRetryOnFormalOrderCreation(t *testing.T) {
 	var callCount int32
 
@@ -211,5 +245,3 @@ func TestSignProxyDoesNotRetryOnFormalOrderCreation(t *testing.T) {
 		t.Fatalf("正式下单接口预期只调用 1 次且不触发重试，实际调用: %d", finalCount)
 	}
 }
-
-