var bytes=window.atob(base64Str.split(",")[1]);//base64Str是base64编码的字符串 var ab = newArrayBuffer(bytes.length); var ia = newUint8Array(ab); for (var i = 0; i < bytes.length; i++) { ia[i] = bytes.charCodeAt(i); } var image = new Blob( [ab] , {type : 'image/png'}); var url = url = URL.createObjectURL(image); var a = document.createElement('a');//这里建一个a标签,用于下面下载图片 a.href = url; a.download = fileName;//fileName是下载的图片名称 var e = document.createEvent('MouseEvents'); e.initMouseEvent('click', true, false, window, 0, 0, 0, 0, 0, false, false, false, false, 0, null); a.dispatchEvent(e);//触发点击事件,开始下载