Iframe自适应高度绝对好使的代码IE,遨游，火狐都兼容，测试过

<script type="text/javascript">

function reinitIframe(){

var iframe = document.getElementById("mainFrame");

try{

var bHeight = iframe.contentWindow.document.body.scrollHeight;

var dHeight = iframe.contentWindow.document.documentElement.scrollHeight;

var height = Math.max(bHeight, dHeight);

iframe.height =  height;

}catch (ex){}

}

window.setInterval("reinitIframe()", 200);

</script>