<html> <head> <title>测试</title> </head> <body> fdfdfadf <table width="200" height="3600" border="1"> <tr> <td>qqxcxcxzc .dfd...,dsfsd,dfds</td> </tr> </table> <div id="a" style="POSITION: absolute;border:1px solid red;">11dsfsdf23</div> <script> function $(id){ return document.getElementById(id); } function getPageTopScroll(){ var yScroll; if (self.pageYOffset) { yScroll = self.pageYOffset; } else if (document.documentElement && document.documentElement.scrollTop){ yScroll = document.documentElement.scrollTop; } else if (document.body) { yScroll = document.body.scrollTop; } return yScroll; } window.onload=function div(){ var aa=getPageTopScroll(); $("a").style.top=aa+document.body.clientHeight/2; setTimeout("div()",100) } </script> </body> </html>