如果你需要改变动画播放速度, 

比如每5秒换一张图片 
改变setTimeout("imgturn('" +numb+ "')", 1000)中的1000为5000 

＜html> 
＜head> 
＜title>＜/title> 

＜script language="JavaScript"> 
＜!-- 
//请先准备几张JPG图片格式的,名字是demo1.jpg,demo2.jpg,demo3.jpg 
if (document.images) { 
demo1 = new Image(); 
demo1.src = "../../images/demo1.jpg"; 

demo2 = new Image(); 
demo2.src = "../../images/demo2.jpg"; 

demo3 = new Image(); 
demo3.src = "../../images/demo3.jpg"; 
} 

function timeimgs(numb) { 
thetimer = setTimeout("imgturn('" +numb+ "')", 1000); 
} 

function imgturn(numb) { 
if (document.images) { 

if (numb == "3") { 
document["demo"].src = eval("demo3.src"); 
timeimgs('1'); 
} 

else { document["demo"].src = eval("demo" + numb + ".src"); 

timeimgs(numb = ++numb); 
} 
} 
} 

// --> 
＜/script> 

＜/head> 
＜body onload="timeimgs('2');"> 

＜img src="../../images/demo1.jpg" name="demo" width="100" height="100" alt="demo">