diff --git a/backend/.env.example b/backend/.env.example
index 6b7b8eb..b4e7ff2 100644
--- a/backend/.env.example
+++ b/backend/.env.example
@@ -56,8 +56,8 @@ REALNAME_CLOUDMARKET_APPCODE=
 # 生成方式：openssl rand -hex 16
 PAYMENT_CONFIG_ENCRYPTION_KEY=
 
-# 开放导入接口签名密钥；留空时 /api/open/listing-uploads 不可用。
-# 请求需携带 X-HFB-Timestamp 和 X-HFB-Signature。
+# 开放导入接口可选签名密钥；留空或请求未带签名时按旧方式导入。
+# 若调用方携带 X-HFB-Timestamp 和 X-HFB-Signature，则会校验 HMAC 签名。
 EXTERNAL_UPLOAD_SECRET=
 # 可选：逗号分隔的 IP 或 CIDR 白名单，例如 127.0.0.1,10.0.0.0/8。
 EXTERNAL_UPLOAD_ALLOWED_IPS=
diff --git a/backend/.env.prod.example b/backend/.env.prod.example
index 2367079..152cf96 100644
--- a/backend/.env.prod.example
+++ b/backend/.env.prod.example
@@ -62,7 +62,8 @@ REALNAME_CLOUDMARKET_APPCODE=
 # 警告：此密钥一旦设置不要更改，否则已有配置无法解密
 PAYMENT_CONFIG_ENCRYPTION_KEY=change-to-32-byte-encryption-key
 
-# 开放导入接口签名密钥，生产环境必填；生成方式：openssl rand -hex 32
-EXTERNAL_UPLOAD_SECRET=change-to-a-long-random-upload-secret
+# 开放导入接口可选签名密钥；内部调用方暂不签名时可留空。
+# 若启用签名，生成方式：openssl rand -hex 32
+EXTERNAL_UPLOAD_SECRET=
 # 可选：逗号分隔的 IP 或 CIDR 白名单，例如 203.0.113.10,10.0.0.0/8。
 EXTERNAL_UPLOAD_ALLOWED_IPS=
diff --git a/backend/internal/config/config.go b/backend/internal/config/config.go
index 31c5cc5..c18c588 100644
--- a/backend/internal/config/config.go
+++ b/backend/internal/config/config.go
@@ -120,9 +120,6 @@ func (c Config) ValidateProductionSecurity() error {
 	if isPlaceholder(c.PaymentConfigEncryptionKey) || (keyLen != 16 && keyLen != 24 && keyLen != 32) {
 		return errors.New("PAYMENT_CONFIG_ENCRYPTION_KEY must be 16, 24, or 32 bytes in production")
 	}
-	if strings.TrimSpace(c.ExternalUploadSecret) == "" || isPlaceholder(c.ExternalUploadSecret) {
-		return errors.New("EXTERNAL_UPLOAD_SECRET is required in production")
-	}
 	if c.BootstrapAdminPassword != "" && isPlaceholder(c.BootstrapAdminPassword) {
 		return errors.New("ADMIN_BOOTSTRAP_PASSWORD must not use the example placeholder in production")
 	}
diff --git a/backend/internal/modules/listing/handler_external.go b/backend/internal/modules/listing/handler_external.go
index 3a90e2b..d3331ea 100644
--- a/backend/internal/modules/listing/handler_external.go
+++ b/backend/internal/modules/listing/handler_external.go
@@ -47,24 +47,26 @@ func (h *Handler) ImportExternalUpload(c *gin.Context) {
 }
 
 var (
-	errExternalUploadSecretMissing = errors.New("external upload secret missing")
-	errExternalUploadForbiddenIP   = errors.New("external upload forbidden ip")
-	errExternalUploadTimestamp     = errors.New("external upload timestamp invalid")
-	errExternalUploadSignature     = errors.New("external upload signature invalid")
+	errExternalUploadForbiddenIP = errors.New("external upload forbidden ip")
+	errExternalUploadTimestamp   = errors.New("external upload timestamp invalid")
+	errExternalUploadSignature   = errors.New("external upload signature invalid")
 )
 
 const externalUploadMaxClockSkew = 5 * time.Minute
 
 func (h *Handler) verifyExternalUpload(c *gin.Context, raw []byte) error {
-	secret := strings.TrimSpace(h.externalUploadSecret)
-	if secret == "" {
-		return errExternalUploadSecretMissing
-	}
 	if !externalUploadIPAllowed(c.ClientIP(), h.externalUploadAllowedIPs) {
 		return errExternalUploadForbiddenIP
 	}
+	secret := strings.TrimSpace(h.externalUploadSecret)
+	if secret == "" {
+		return nil
+	}
 	timestamp := strings.TrimSpace(c.GetHeader("X-HFB-Timestamp"))
 	signature := strings.TrimSpace(c.GetHeader("X-HFB-Signature"))
+	if timestamp == "" && signature == "" {
+		return nil
+	}
 	if timestamp == "" || signature == "" {
 		return errExternalUploadSignature
 	}
@@ -111,8 +113,6 @@ func externalUploadIPAllowed(clientIP string, allowed []string) bool {
 
 func writeExternalUploadAuthError(c *gin.Context, err error) {
 	switch err {
-	case errExternalUploadSecretMissing:
-		response.ServiceUnavailable(c, "开放导入签名密钥未配置")
 	case errExternalUploadForbiddenIP:
 		response.Error(c, http.StatusForbidden, "forbidden", "来源 IP 不允许访问")
 	case errExternalUploadTimestamp:
diff --git a/backend/internal/modules/listing/handler_external_test.go b/backend/internal/modules/listing/handler_external_test.go
index 37645f4..c774501 100644
--- a/backend/internal/modules/listing/handler_external_test.go
+++ b/backend/internal/modules/listing/handler_external_test.go
@@ -30,6 +30,28 @@ func TestVerifyExternalUploadSignature(t *testing.T) {
 	}
 }
 
+func TestVerifyExternalUploadAllowsUnsignedRequest(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	c, _ := gin.CreateTestContext(httptest.NewRecorder())
+	c.Request = httptest.NewRequest("POST", "/api/open/listing-uploads", nil)
+
+	handler := &Handler{}
+	if err := handler.verifyExternalUpload(c, []byte(`{}`)); err != nil {
+		t.Fatalf("verifyExternalUpload() error = %v", err)
+	}
+}
+
+func TestVerifyExternalUploadAllowsUnsignedRequestWithSecret(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	c, _ := gin.CreateTestContext(httptest.NewRecorder())
+	c.Request = httptest.NewRequest("POST", "/api/open/listing-uploads", nil)
+
+	handler := &Handler{externalUploadSecret: "test-upload-secret"}
+	if err := handler.verifyExternalUpload(c, []byte(`{}`)); err != nil {
+		t.Fatalf("verifyExternalUpload() error = %v", err)
+	}
+}
+
 func TestVerifyExternalUploadRejectsBadSignature(t *testing.T) {
 	gin.SetMode(gin.TestMode)
 	c, _ := gin.CreateTestContext(httptest.NewRecorder())