diff --git a/packages/midway-decorator/src/faas/fun.ts b/packages/midway-decorator/src/faas/fun.ts
index 0610880e96a3..c8b8829e2879 100644
--- a/packages/midway-decorator/src/faas/fun.ts
+++ b/packages/midway-decorator/src/faas/fun.ts
@@ -11,8 +11,8 @@ export interface FuncParams {
 
 export function Func(
   funHandler: string | FuncParams,
-  functionOptions: FuncParams | undefined
-): ClassDecorator {
+  functionOptions?: FuncParams
+) {
   if (typeof funHandler !== 'string' && functionOptions === undefined) {
     functionOptions = funHandler;
     funHandler = '';