Try this code..
i am able to get the full path..
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title></title>
<script src="JQuery.js" type="text/javascript"></script>
<script type="text/javascript">
$(function () {
$('#btn').click(function () {
alert($('input[type=file]').val());
return false;
});
});
</script>
</head>
<body>
<form id="form1" runat="server">
<asp:Button ID="btn" runat="server" Text="some" />
<asp:FileUpload ID="FileUpload1" runat="server" />
</form>
</body>
</html>