<!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" /><title>动画菜单</title><style type="text/css">* { margin: 0; padding: 0; font-size: 14px; }a { color: #333; text-decoration: none }ul{ list-style: none; }.nav {height: 30px; border-bottom: 5px solid #F60; margin-left:50px; width:600px;}.nav li { float: left; position:relative; height:30px; width:120px }.nav li a { display: block; height: 30px; text-align: center; line-height: 30px; width:120px; background: #efefef; margin-left: 1px; }.subNav{ position:absolute; top:30px; left:0; width:120px; height:0; overflow:hidden}.subNav li a{ background:#ddd }.subNav li a:hover{ background:#efefef}</style><script type="text/javascript" src="https://code.jquery.com/jquery-3.4.1.min.js"></script><script>$(function(){ var curHeight = $(this).height(); $("li:has('ul')").hover( function(){ $(this).children("ul").animate({"height":curHeight},30); }, function(){ $(this).children("ul").animate({"height":"0"},30); } )})</script></head><body><ul class="nav"> <li><a href="#">一级菜单</a> <ul class="subNav"> <li><a href="#">二级菜单</a></li> <li><a href="#">二级菜单</a></li> <li><a href="#">二级菜单</a></li> <li><a href="#">二级菜单</a></li> </ul> </li> <li><a href="#">一级菜单</a> <ul class="subNav"> <li><a href="#">二级菜单</a></li> <li><a href="#">二级菜单</a></li> <li><a href="#">二级菜单</a></li> <li><a href="#">二级菜单</a></li> </ul> </li> <li><a href="#">一级菜单</a></li> <li><a href="#">一级菜单</a></li> <li><a href="#">一级菜单</a></li></ul></body></html>