且把包含图片的div中的display属性设置成table-cell，最后给有图片的div设置成vertical-align:
middle属性，代码如下：
.tablebox{
width: 300px
height: 250px
background: #fff
display: table
}
#xxx{
display: table-cell
vertical-align: middle
}
#xxx img{
width: 100px
}
可以多看看黑马程序员的课程，多学学这些基础知识。
<!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>
<title>title</title>
<meta name="author" content="" />
<meta name="keywords" content="" />
<meta name="description" content="" />
<meta http-equiv="content-type" content="text/htmlcharset=utf-8" />
<style type="text/css">
.content {width:200pxheight:100pxoverflow:hiddenbackground-color:#fafafa}
.content img {display:blockmargin:0 auto}
</style>
<script type="text/javascript">
</script>
</head>
<body>
<div class="content">
<div><img src="tt.jpg"><div>
</div>
</body>
</html>
<!--上述代码兼容ie6,7,8,ff, safari, opera, chrome! -->
