<input type="radio" name="radio" value="1">单选1
<input type="radio" name="radio" value="2">单选2
<input type="radio" name="radio" value="3" checked>单选3
<input type="radio" name="radio" value="4">单选4/**注意：name值一定要相同才能够单选，要默认选项，加一个属性checked就行了**/html中<radio>单选按钮控件标签用法解析及如何设置默认选中
原文：http://www.cnblogs.com/ninsh1992/p/6247542.html