<input type="submit" name="Submit" value="发送" id="abc" onclick="test();">
<script language="javascript">
function test()
{
var abc=document.getElementById('abc');
abc.disabled=true; //变灰
document.form1.submit();
setTimeout("abc.disabled=false;",3000); //代码核心在这里，3秒后还原
}
</script>