<form id="form1" name="form1" method="post" action="">
<select name="select" id="select" onchange="window.location=this.value;">
<option value="http://www.baidu.com">百度</option>
<option value="http://www.cnblogs.com">博客园</option>
</select>
</form>
原文：https://www.cnblogs.com/ince/p/9527141.html