diff --git a/lib/qrcode.js b/lib/qrcode.js
index 2514aaa..b36e22f 100644
--- a/lib/qrcode.js
+++ b/lib/qrcode.js
@@ -759,18 +759,12 @@
         console.warn('No canvas provided to draw QR code in!')
         return;
       }
-      //边框大小
-      const BORDER_SIZE = 0;
       var size = Math.min(cavW, cavH);
       str = that.utf16to8(str);//增加中文显示
 
-      var frame = that.getFrame(str),
+      var frame = that.getFrame(str);
         // 组件中生成qrcode需要绑定this 
-        px = Math.round(size / (width + BORDER_SIZE));
-      var roundedSize = px * (width + 8),
-        offset = Math.floor((size - roundedSize) / 2);
-      size = roundedSize;
-      //ctx.clearRect(0, 0, cavW, cavW);
+      var px = size / width;
       if (bg) {
         ctx.setFillStyle(bg)
         ctx.fillRect(startX, startY, cavW, cavW);
@@ -779,7 +773,7 @@
       for (var i = 0; i < width; i++) {
         for (var j = 0; j < width; j++) {
           if (frame[j * width + i]) {
-            ctx.fillRect(startX + px * (4 + i) + offset, startY + px * (4 + j) + offset, px, px);
+            ctx.fillRect(startX + px * i, startY + px * j, px, px);
           }
         }
       }