Div+CSS+JS组和能够实现很多好看的特殊的效果，这里推荐一款可刷新的下拉菜单：

下面是js代码部分：

<script type=text/javascript><!--

var LastLeftID = "";
function menuFix() {
 var obj = document.getElementById("nav").getElementsByTagName("li");
 for (var i=0; i<obj.length; i++) {
  obj[i].onmouseover=function() {
   this.className+=(this.className.length>0? " ": "") + "sfhover";
  }

  obj[i].onMouseDown=function() {
   this.className+=(this.className.length>0? " ": "") + "sfhover";
  }

  obj[i].onMouseUp=function() {
   this.className+=(this.className.length>0? " ": "") + "sfhover";
  }

  obj[i].onmouseout=function() {
   this.className=this.className.replace(new RegExp("( ?|^)sfhover\\b"), "");
  }
 }
}

function DoMenu(emid)
{
 var obj = document.getElementById(emid);
 obj.className = (obj.className.toLowerCase() == "expanded"?"collapsed":"expanded");
 if((LastLeftID!="")&&(emid!=LastLeftID)) //关闭上一个Menu

 {
  document.getElementById(LastLeftID).className = "collapsed";
 }
 LastLeftID = emid;
}

function GetMenuID()
{
 var MenuID="";
 var _paramStr = new String(window.location.href);
 var _sharpPos = _paramStr.indexOf("#");
 if (_sharpPos >= 0 && _sharpPos < _paramStr.length - 1)
 {
  _paramStr = _paramStr.substring(_sharpPos + 1, _paramStr.length);
 }
 else
 {
  _paramStr = "";
 }
 if (_paramStr.length > 0)
 {
  var _paramArr = _paramStr.split("&");
  if (_paramArr.length>0)
  {
   var _paramKeyVal = _paramArr[0].split("=");
   if (_paramKeyVal.length>0)
   {
    MenuID = _paramKeyVal[1];
   }
  }
  /*
  if (_paramArr.length>0)
  {
   var _arr = new Array(_paramArr.length);
  }
  //取所有#后面的，菜单只需用到Menu
  //for (var i = 0; i < _paramArr.length; i++)
  {
   var _paramKeyVal = _paramArr[i].split(’=’);
   if (_paramKeyVal.length>0)
   {
    _arr[_paramKeyVal[0]] = _paramKeyVal[1];
   } 
  }
  */
 }
 if(MenuID!="")
 {
  DoMenu(MenuID)
 }

}
GetMenuID(); //*这两个function的顺序要注意一下，不然在Firefox里GetMenuID()不起效果

menuFix();

--></script>

完整的代码演示：

<title>可刷新的Div+CSS+JS二级下拉树型菜单 - 中国asp之家</title> <style type="text/css"> <!-- *{margin:0;padding:0;border:0;} body { font-family: arial, 宋体, serif; font-size:12px; } #nav { width:180px; line-height: 24px; list-style-type: none; text-align:left; /*定义整个ul菜单的行高和背景色*/ } /*==================一级目录===================*/ #nav a { width: 160px; display: block; padding-left:20px; /*Width(一定要)，否则下面的Li会变形*/ } #nav li { background:#CCC; /*一级目录的背景色*/ border-bottom:#FFF 1px solid; /*下面的一条白边*/ float:left; /*float：left,本不应该设置，但由于在Firefox不能正常显示 继承Nav的width,限制宽度，li自动向下延伸*/ } #nav li a:hover{ background:#CC0000; /*一级目录onMouseOver显示的背景色*/ } #nav a:link { color:#666; text-decoration:none; } #nav a:visited { color:#666;text-decoration:none; } #nav a:hover { color:#FFF;text-decoration:none;font-weight:bold; } /*==================二级目录===================*/ #nav li ul { list-style:none; text-align:left; } #nav li ul li{ background: #EBEBEB; /*二级目录的背景色*/ } #nav li ul a{ padding-left:20px; width:160px; /* padding-left二级目录中文字向右移动，但Width必须重新设置=(总宽度-padding-left)*/ } /*下面是二级目录的链接样式*/ #nav li ul a:link { color:#666; text-decoration:none; } #nav li ul a:visited { color:#666;text-decoration:none; } #nav li ul a:hover { color:#F3F3F3; text-decoration:none; font-weight:normal; background:#CC0000; /* 二级onmouseover的字体颜色、背景色*/ } /*==============================*/ #nav li:hover ul { left: auto; } #nav li.sfhover ul { left: auto; } #content { clear: left; } #nav ul.collapsed { display: none; } --> #PARENT{ width:300px; padding-left:20px; } </style> <div id="PARENT"> <ul id="nav"> <li><a href="#Menu=ChildMenu1" onclick="DoMenu('ChildMenu1')">我的网站</a> <ul id="ChildMenu1" class="collapsed"> <li><a href="http://www.aspxhome.com" target="_blank">中国asp之家</a></li> <li><a target="_self" href="http://www.aspxhome.com/asp/">Asp编程</a></li> <li><a target="_self" href="http://www.aspxhome.com/asp-net/">Asp.net</a></li> <li><a target="_self" href="http://www.aspxhome.com/javascript/"> JavaScript</a></li> <li><a target="_self" href="http://www.aspxhome.com/design/">网页设计</a></li> <li><a target="_self" href="http://www.aspxhome.com/webmaster/">站长必读</a></li> </ul> </li> <li><a href="#Menu=ChildMenu2" onclick="DoMenu('ChildMenu2')">Asp之家</a> <ul id="ChildMenu2" class="collapsed"> <a href="http://www.aspxhome.com" target="_blank">支付</a></li> <li><a target="_self" href="http://www.aspxhome.com/download/">下载中心</a></li> <li><a target="_self" href="http://www.aspxhome.com/asp/">Asp编程</a></li> <li><a target="_self" href="http://www.aspxhome.com/asp-net/">Asp.net</a></li> <li><a target="_self" href="http://www.aspxhome.com/javascript/"> JavaScript</a></li> <li><a target="_self" href="http://www.aspxhome.com/design/">网页设计</a></li> <li><a target="_self" href="http://www.aspxhome.com/webmaster/">站长必读</a></li> </ul> </li> <li><a href="#Menu=ChildMenu3" onclick="DoMenu('ChildMenu3')">网站管理</a> <ul id="ChildMenu3" class="collapsed"> <li><a href="#">登录</a></li> <a href="http://www.aspxhome.com" target="_blank">管理</a></li> <li><a href="#">管理</a></li> <li><a href="#">管理</a></li> </ul> </li> <li><a href="#Menu=ChildMenu4" onclick="DoMenu('ChildMenu4')">网站管理</a> <ul id="ChildMenu4" class="collapsed"> <li><a href="#">登录</a></li> <a href="http://www.aspxhome.com" target="_blank">管理</a></li> <li><a href="#">管理</a></li> <li><a href="#">管理</a></li> <li><a href="#">管理</a></li> </ul> </li> </ul> </div> <script type=text/javascript><!-- var LastLeftID = ""; function menuFix() { var obj = document.getElementById("nav").getElementsByTagName("li"); for (var i=0; i<obj.length; i++) { obj[i].onmouseover=function() { this.className+=(this.className.length>0? " ": "") + "sfhover"; } obj[i].onMouseDown=function() { this.className+=(this.className.length>0? " ": "") + "sfhover"; } obj[i].onMouseUp=function() { this.className+=(this.className.length>0? " ": "") + "sfhover"; } obj[i].onmouseout=function() { this.className=this.className.replace(new RegExp("( ?|^)sfhover\\b"), ""); } } } function DoMenu(emid) { var obj = document.getElementById(emid); obj.className = (obj.className.toLowerCase() == "expanded"?"collapsed":"expanded"); if((LastLeftID!="")&&(emid!=LastLeftID)) //关闭上一个Menu { document.getElementById(LastLeftID).className = "collapsed"; } LastLeftID = emid; } function GetMenuID() { var MenuID=""; var _paramStr = new String(window.location.href); var _sharpPos = _paramStr.indexOf("#"); if (_sharpPos >= 0 && _sharpPos < _paramStr.length - 1) { _paramStr = _paramStr.substring(_sharpPos + 1, _paramStr.length); } else { _paramStr = ""; } if (_paramStr.length > 0) { var _paramArr = _paramStr.split("&"); if (_paramArr.length>0) { var _paramKeyVal = _paramArr[0].split("="); if (_paramKeyVal.length>0) { MenuID = _paramKeyVal[1]; } } /* if (_paramArr.length>0) { var _arr = new Array(_paramArr.length); } //取所有#后面的，菜单只需用到Menu //for (var i = 0; i < _paramArr.length; i++) { var _paramKeyVal = _paramArr[i].split(’=’); if (_paramKeyVal.length>0) { _arr[_paramKeyVal[0]] = _paramKeyVal[1]; } } */ } if(MenuID!="") { DoMenu(MenuID) } } GetMenuID(); //*这两个function的顺序要注意一下，不然在Firefox里GetMenuID()不起效果 menuFix(); --></script> [提示：你可先修改部分代码，再按运行]

您可以根据需要把这个二级下拉树型菜单改成你自己喜欢的样式。