<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8" />
<title>Document</title>
<style type="text/css">
body{
background: #f14849;
}
div{
position: relative;
width: 300px;
height: 300px;
margin:100px auto;
}
div img{
position: absolute;
top:0;
left:0;
transition:all 1s;
backface-visibility:hidden;
}
/*
1、先把背面(bg01)的图片，先翻转180deg 隐藏
2、鼠标移入，让前面(bg02)的图片，翻转180deg 隐藏
3、再让bg01 翻转回0deg
*/
div img:nth-of-type(1){transform:rotateY(180deg);}
div:hover img:nth-of-type(2){
transform:rotateY(180deg);
}
div:hover img:nth-of-type(1){
transform:rotateY(0deg);
}
</style>
</head>
<body>
<div>
<img src="img/bg01.png" >
<img src="img/bg02.png" >
</div>
</body>
</html>图片规格: 300px * 300px