<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<style>
html, body, ul, li, h1, h2, h3, h4, h5, h6, fieldset, legend {padding:0; margin:0;}
body {font:12px/normal Verdana, Arial, Helvetica, sans-serif;}
ul li{list-style-type:none;text-transform:capitalize;}
#nav .mainlevel{float:left;margin-right:20px;padding-right:3px;background:#ffff00;140px;text-align:center; line-height:22px;}
.linHideStyle{display:none;}
</style>
<script type="text/javascript" src="./jquery/jquery-1.7.1.min.js"></script>
<script>
$(document).ready(function(){
$('li.mainlevel').mousemove(function(){
$(this).find('ul').removeClass('linHideStyle').slideDown();//you can give it a speed
});
$('li.mainlevel').mouseleave(function(){
$(this).find('ul').addClass('linHideStyle').slideUp("fast");
});
});
</script>
<title>jquery下拉竖导航菜单代码</title>
</head>
<body>
<br /><br /><br />
<div id="menu">
<ul id="nav">
<li id="mainlevel_01" class="mainlevel">
<a href="#">第一</a>
<ul class="linHideStyle">
<li>
<a href="">the one</a>
</li>
<li>
<a href="">the one</a>
</li>
<li>
<a href="">the one</a>
</li>
</ul>
</li>
<li id="mainlevel_02" class="mainlevel">
<a href="#">第二</a>
<ul class="linHideStyle">
<li>
<a href="">the one</a>
</li>
<li>
<a href="">3333dd</a>
</li>
<li>
<a href="">the one</a>
</li>
</ul>
</li>
<li id="mainlevel_03" class="mainlevel">
<a href="#">第三</a>
<ul class="linHideStyle">
<li>
<a href="">the one</a>
</li>
<li>
<a href="">the one</a>
</li>
<li>
<a href="">the one</a>
</li>
</ul>
</li>
<li id="mainlevel_04" class="mainlevel">
<a href="#">第四季度</a>
<ul class="linHideStyle">
<li>
<a href="">the one</a>
</li>
<li>
<a href="">the one</a>
</li>
<li>
<a href="">the one</a>
</li>
</ul>
</li>
</ul>
</div>
</body>
</html>