<div class="personal_switch_tit mb15">
        <ul>
            <li><a href="a.aspx" target="mainFrame" class="mo13">A</a></li>
            <li><a href="b.aspx" target="mainFrame" >B</a></li>
            <li><a href="c.aspx" target="mainFrame">C </a></li>
            <li><a href="d.aspx" target="mainFrame">D </a></li>
            <li><a href="e.aspx" target="mainFrame">E</a></li>
        </ul>
    </div>

    <iframe id="mainFrame" name="mainFrame" src="A.aspx" scrolling="no" frameborder="0" height="100%" width="100%" onload='IFrameReSize("mainFrame");'></iframe>
 

JS

//iframe高度自適應
function IFrameReSize(iframename) {
    var pTar = document.getElementById(iframename);
    if (pTar) {  //ff
        if (pTar.contentDocument && pTar.contentDocument.body.offsetHeight) {
            pTar.height = pTar.contentDocument.body.offsetHeight;
        } //ie
        else if (pTar.Document && pTar.Document.body.scrollHeight) {
            pTar.height = pTar.Document.body.scrollHeight;
        }
    }
}