<div id="wai">
<div id="wai_a1">
<img class="img" src="../图片/张掖丹霞7.jpeg" width="640px" height="400px" />
<img class="img" src="../图片/丹霞1.jpg" width="640px" height="400px" />
<img class="img" src="../图片/丹霞4.jpg" width="640px" height="400px" />
</div>
<div id="wai_a2">
<div class="wai_a2_a">
<img src="../图片/张掖丹霞3.jpeg" width="360px" height="200px"/>
</div>
<div class="wai_a2_a">
<img src="../图片/丹霞3.jpg" width="360px" height="200px" />
</div>
</div>
</div>
var index=0; var img=document.getElementsByClassName("img"); huan(); function huan(){ //xianshi(); for(var i=0;i<img.length;i++){ img[i].style.display="none"; } img[index].style.display="block"; if(index>=img.length-1){ index=0; } else{ index++; } window.setTimeout("huan()",2000); } /*function xianshi(){ for(var i=0;i<img.length;i++){ img[i].style.display="none"; } img[index].style.display="block"; }*/
原文：http://www.cnblogs.com/jgjk/p/7106902.html