В самом простом виде так:
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" dir="ltr">
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8"/>
<link rel="stylesheet" href="jquery.plupload.queue/css/jquery.plupload.queue.css" type="text/css" media="screen" />
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.5.1/jquery.min.js"></script>
<script type="text/javascript" src="http://bp.yahooapis.com/2.4.21/browserplus-min.js"></script>
<script type="text/javascript" src="../js/plupload.js"></script>
<script type="text/javascript" src="../js/plupload.flash.js"></script>
<script type="text/javascript" src="../js/plupload.html5.js"></script>
<script type="text/javascript" src="../js/jquery.plupload.queue/jquery.plupload.queue.js"></script>
</head>
<body>
<select id="descript1" name="descript1"><option value="1">1</option><option value="2">2</option><option value="3">3</option></select>
<form>
<div>
<div id="html5_uploader" style="width: 450px; height: 330px;">You browser doesn't support native upload. Try Firefox 3 or Safari 4.</div>
</div>
</form>
<script type="text/javascript">
$(function() {
$("#html5_uploader").pluploadQueue({
runtimes : 'html5',
url : 'upload.php',
max_file_size : '10mb',
multipart_params: {"description1": $("select[name=descript1]").val()},
});
});
</script>
</body>
</html>