可以用流下載(耗內存，少用)或直接轉到該文件.
<%
Const USE_STREAM = 0 '0.不用流(Adodb.Stream)下載1.用流下載
Const ALLOW_FILE_EXT = "rar,zip,chm,doc,xls,swf,mp3,gif,jpg,jpeg,png,bmp" '允許下載的檔案的副檔名，防止原始程式碼被下載
Dim sDownFilePath '下載檔案路徑
sDownFilePath = Trim(Request("FilePath"))
'或根據傳過來的檔案ID從資料庫取得檔案路徑
'如果sDownFilePath 為絕對路徑，一定要將sDownFilePath 轉換為相對本檔案的相對路徑
'sDownFilePath = "focus.swf"
Call DownloadFile(sDownFilePath)
Function DownloadFile(s_DownFilePath )
'判斷有沒傳遞檔名
If IsNull(s_DownFilePath) = True Or Trim(s_DownFilePath) = "" Then
OutputErr "錯誤：先確定要下載的文件，下載失敗"
End If
'判斷副檔名是否合法
Dim s_FileExt
s_FileExt = Mid(s_DownFilePath, InstrRev(s_DownFilePath, ".")+1)
If InStr("," & ALLOW_FILE_EXT & ",", "," & s_FileExt & ",") <= 0 Then
OutputErr "錯誤：檔案類型（" & s_FileExt & "）不允許下載，下載失敗"
End If
s_DownFilePath = Replace(s_DownFilePath, "", "/")
'為了安全，某些目錄禁止下載文件，在這裡處理
'
'檢測伺服器是否支援fso
Dim o_Fso
On Error Resume Next
Set o_Fso = Server.CreateObject("Scripting.FileSystemObject")
If Err.Number <> 0 Then
Err.Clear
OutputErr "錯誤：伺服器不支援fso元件，下載失敗"
End If
'取得檔名，檔案大小
Dim s_FileMapPath
Dim o_File, s_FileName, n_FileLength
s_FileMapPath = Server.MapPath(s_DownFilePath)
If (o_Fso.FileExists(s_FileMapPath)) = True Then
Set o_File = o_Fso.GetFile(s_FileMapPath)
s_FileName = o_File.Name
n_FileLength = o_File.Size
o_File.Close
Else
OutputErr "錯誤：檔案不存在，下載失敗"
End If
Set o_Fso = Nothing
'判斷是否下載的檔案大小超過限制
'
'如果不是用流下載，直接轉到該文件
If USE_STREAM = 0 Then
Response.Redirect sDownFilePath
Response.end
End If
'偵測伺服器是否支援Adodb.Stream
On Error Resume Next
Set o_Stream = Server.CreateObject("Adodb.Stream")
If Err.Number <> 0 Then
Err.Clear
OutputErr "錯誤：伺服器不支援Adodb.Stream元件，下載失敗"
End If
o_Stream.Tyep = 1
o_Stream.Open
o_Stream.LoadFromFile s_FileMapPath
Response.Buffer = True
Response.Clear
Response.AddHeader "Content-Disposition", "attachment; filename=" & s_FileName
Response.AddHeader "Content-Length", n_FileLength
Response.CharSet = "UTF-8"
Response.ContentType = "application/octet-stream"
Response.BinaryWrite o_Stream.Read
Response.Flush
o_Stream.Close
Set o_Stream = Nothing
End Function
Sub OutputErr(s_ErrMsg)
Response.Write "<font color=red>" & s_ErrMsg & "</font>"
Response.End
End Sub
%>
http://www.cnblogs.com/jiny-z/archive/2006/08/29/489102.html