<!DOCTYPE HTML>
<html lang="en-US">
<head>
<meta charset="UTF-8">
<title>easonjim</title>
<script src="scripts/jquery.js" type="text/javascript"></script>
</head>
<body>
<select id='province'>
<option value='6'>66
<option value='7'>77
<option value='8'>88
</select>
<input type='button' id="btn1" value='setPi'>
<script type="text/javascript">
$('#province').on("change", function () {
alert($('#province').get(0).selectedIndex);
});
$('#btn1').on("click", function () {
$('#province').get(0).selectedIndex = 1;
$('#province').trigger("change");
});
</script>
</body>
</html>