IE8 以下浏览器实现圆角div样式

 .yuan
        {
            border: 2px solid #fff;
            -moz-border-radius: 30px;
            -webkit-border-radius: 30px;
            border-radius: 30px;
            position: relative;
            padding: 5px;
            background: #FFF;
            z-index: 2;
            behavior: url(../Scripts/ie-css3.htc);
        }

  <div   class="yuan"  >
     </div>

还需引入ie-css3.htc文件即可