<script language="javascript">
function keyEnter(){
if(window.event.keyCode==13){
window.event.keyCode=9;
}
}
function keyEnter(){
if(window.event.keyCode==13){
window.event.keyCode=9;
}
}
</script>
例:<asp:TextBox ID="txt_SheetNO_S" runat="server" onkeydown="keyEnter()" ></asp:TextBox>