try try this..

Public Function ToDataSetbyOle(pathName As String, SheetName As String) As DataSet

	Dim strQuery As String = "SELECT * FROM [" & SheetName & "]"
	Dim conn As New System.Data.OleDb.OleDbConnection("Provider=Microsoft.Jet.OleDb.4.0; Data Source = " & pathName & "; Extended Properties = ""Excel;HDR=YES;FMT=""")
	conn.Open()
	Dim adapter As New System.Data.OleDb.OleDbDataAdapter(strQuery, conn)
	Dim ds As New System.Data.DataSet("Excel File")
	adapter.Fill(ds)
	conn.Close()
	Return ds

End Function

DropDownlist1.DataSource = dataSet.Tables("Table1")
Dropdownlist1.DataTextField = "username"
Dropdownlist1.DataValueField = "userid"
DropDownlist1.DataBind()

http://forums.asp.net/t/1255191.aspx/1