Hi,
Yeah we can do that.If we use javascript that is possible.
just place this code in your page...
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<script src="../Scripts/jquery-1.4.1-vsdoc.js" type="text/javascript"></script>
<script src="../Scripts/jquery-1.4.1.js" type="text/javascript"></script>
<script language ="javascript" >
function f1() {
$("#fileup1").click();
}
</script>
</head>
<body>
<form id="form1" runat="server">
<asp:scriptmanager id="ScriptManager1" runat="server" xmlns:asp="#unknown">
</asp:scriptmanager>
<input type ="button" value ="put" onclick="f1()" />
<input type="file" id="fileup1" style =" visibility :hidden ;"/>
</form>
</body>
</html>
I hope it can works for you also
All the Best