<iframe id="iframe" src="http://www.imooc.com/wiki/html5/forms.html?preview=d2269b100476b4b77b9ddc11242e85ab" frameborder="1"></iframe><!--src的域名需要和当前网页域名一直，否则跨域不能获取iframe的contentWindow--> <script> var iframe = document.getElementById("iframe");//获取iframe的dom节点 iframe.onload = function(){ var doc = this.contentWindow.document; this.height = doc.documentElement.scrollHeight;//高度动态设置 this.width = doc.documentElement.scrollWidth;//宽度动态设置 } </script>