diff --git a/library/src/main/ets/model/ImageKnifeOption.ets b/library/src/main/ets/model/ImageKnifeOption.ets
index 0cf9dde..4e42b00 100644
--- a/library/src/main/ets/model/ImageKnifeOption.ets
+++ b/library/src/main/ets/model/ImageKnifeOption.ets
@@ -124,7 +124,7 @@ export class ImageKnifeOption {
   onComplete?:(event:EventImage | undefined) => void
   drawingColorFilter?: ColorFilter | drawing.ColorFilter
   // 下采样
-  @Trace downsampleOf?: DownsampleStrategy = DownsampleStrategy.NONE
+  @Trace downsampleOf: DownsampleStrategy = DownsampleStrategy.NONE
   constructor(option?:ImageOption) {
     this.loadSrc = option?.loadSrc == undefined ? "" : option?.loadSrc
     this.placeholderSrc = option?.placeholderSrc
@@ -145,7 +145,7 @@ export class ImageKnifeOption {
     this.onLoadListener = option?.onLoadListener
     this.onComplete = option?.onComplete
     this.drawingColorFilter = option?.drawingColorFilter
-    this.downsampleOf = option?.downsampleOf
+    this.downsampleOf = option?.downsampleOf==undefined?DownsampleStrategy.NONE:option?.downsampleOf
   }
 }