<!DOCTYPE html>
<html>
<head>
<script type='text/javascript'
src='http://code.jquery.com/jquery-1.6.js'></script>
<script type='text/javascript'>
$(window).load(function(){
$radio = $('#radio2');
$radio.get(0).checked = true;
});
</script>
</head>
<body>
<input id="radio1" type="radio" name="mybtn" value="0" />0
<br />
<input id="radio2" type="radio" name="mybtn" value="1" />1
</body>
</html>