Public Function AutoCompactCurrentProject()
    Dim fs, f, s, filespec
    Dim strProjectPath As String, strProjectName As String
    strProjectPath = Application.CurrentProject.Path
    strProjectName = Application.CurrentProject.Name
    filespec = strProjectPath & "\" & strProjectName
    Set fs = CreateObject("Scripting.FileSystemObject")
    Set f = fs.GetFile(filespec)
    s = CLng(f.Size / 1000000)  ‘转换文件大小为MB
    If s > 20 Then                       ‘修改此处的20M为你自己需要的值
        Application.SetOption ("Auto Compact"), 1  ‘压缩程序
    Else
        Application.SetOption ("Auto Compact"), 0   ‘不压缩程序
    End If
End Function

在任何退出的程序前调用这个函数，例如在Docmd.Quit前调用：
AutoCompactCurrentProject