diff --git a/lib/pen.js b/lib/pen.js
index 3d7b3b7..cb0d980 100644
--- a/lib/pen.js
+++ b/lib/pen.js
@@ -34,8 +34,8 @@ export default class Painter {
 
     this._doClip(this.data.borderRadius, width, height);
     if (!bg) {
-      // 如果未设置背景，则默认使用白色
-      this.ctx.fillStyle = '#fff';
+      // 如果未设置背景，则默认使用透明色
+      this.ctx.fillStyle = 'transparent';
       this.ctx.fillRect(-(width / 2), -(height / 2), width, height);
     } else if (bg.startsWith('#') || bg.startsWith('rgba') || bg.toLowerCase() === 'transparent') {
       // 背景填充颜色
diff --git a/painter.js b/painter.js
index 4f2efe5..7fc1c89 100644
--- a/painter.js
+++ b/painter.js
@@ -130,17 +130,22 @@ Component({
           background: this.currentPalette.background,
           views: bottomLayers
         }
-        new Pen(wx.createCanvasContext('bottom', this), bottomDraw).paint();
-
         const topDraw = {
           width: this.currentPalette.width,
           height: this.currentPalette.height,
           views: topLayers
         }
-        new Pen(wx.createCanvasContext('top', this), topDraw).paint();
+        if (this.prevFindedIndex < findedIndex) {
+          new Pen(wx.createCanvasContext('bottom', this), bottomDraw).paint();
+          new Pen(wx.createCanvasContext('top', this), topDraw).paint();
+        } else {
+          new Pen(wx.createCanvasContext('top', this), topDraw).paint();
+          new Pen(wx.createCanvasContext('bottom', this), bottomDraw).paint();
+        }
 
         this.doAction()
       }
+      this.prevFindedIndex = findedIndex
     },
 
     onTouchEnd() {
diff --git a/painter.wxml b/painter.wxml
index 8c173b7..e22af0a 100644
--- a/painter.wxml
+++ b/painter.wxml
@@ -1,6 +1,12 @@
-<canvas canvas-id="k-canvas" 
-  style="{{painterStyle}}{{customStyle}}" 
-  bindtouchstart="onTouchStart"
-  bindtouchmove="onTouchMove"
-  bindtouchend="onTouchEnd"
-  bindtouchcancel="onTouchCancel"/>
\ No newline at end of file
+<view style='position: relative;{{painterStyle}}{{customStyle}}'>
+  <canvas canvas-id="bottom" style="{{painterStyle}};position: absolute;" />
+  <canvas canvas-id="k-canvas" style="{{painterStyle}};position: absolute;" />
+  <canvas 
+    canvas-id="top" 
+    style="{{painterStyle}};position: absolute;"
+    bindtouchstart="onTouchStart"
+    bindtouchmove="onTouchMove"
+    bindtouchend="onTouchEnd"
+    bindtouchcancel="onTouchCancel"
+    disable-scroll="{{true}}" />
+</view>
\ No newline at end of file