<script type="text/javascript" src="jquery-1.5.2.min.js"></script>

<style>

    table{border-collapse:collapse;}

    table td{border: 1px solid black;}

 </style>

 <table cellspacing="0" cellpadding="0" id="aaa">

   <tr>

 <td>&nbsp;&nbsp;</td><td>&nbsp;&nbsp;</td><td>&nbsp;&nbsp;</td>

   </tr>



    <tr>

 <td>&nbsp;&nbsp;</td><td>&nbsp;&nbsp;</td><td>&nbsp;&nbsp;</td>

   </tr>

    <tr>

 <td>&nbsp;&nbsp;</td><td>&nbsp;&nbsp;</td><td>&nbsp;&nbsp;</td>

   </tr>

 </table>

 <script>

 $(function(){

 setTblNo("aaa");

 })

 function setTblNo(tblid)

 {

	var oTbl=$("#"+tblid);

	oTbl.find("tr:first >td").css("border-top","none");//去掉上边框

	oTbl.find("tr:last >td").css("border-bottom","none");//去掉下边框

	oTbl.find("tr >td:first-child").css("border-left","none");//去掉左边框

	oTbl.find("tr >td:last-child").css("border-right","none");//去掉右边框

 }

 </script>