这也太。。。复杂了吧，其实不用那么复杂：
Option Explicit
Private Declare Function GetOpenFileName Lib "comdlg32.dll" Alias _
"GetOpenFileNameA" (pOpenfilename As OPENFILENAME) As Long
Type OPENFILENAME
lStructSize As Long
hwndOwner As Long
hInstance As Long
lpstrFilter As String
lpstrCustomFilter As String
nMaxCustFilter As Long
nFilterIndex As Long
lpstrFile As String
nMaxFile As Long
lpstrFileTitle As String
nMaxFileTitle As Long
lpstrInitialDir As String
lpstrTitle As String
flags As Long
nFileOffset As Integer
nFileExtension As Integer
lpstrDefExt As String
lCustData As Long
lpfnHook As Long
lpTemplateName As String
End Type
Dim ofn As OPENFILENAME
Dim rtn As String
ofn.lStructSize = Len(ofn)
ofn.hwndOwner = Me.hWnd
ofn.hInstance = App.hInstance
ofn.lpstrFilter = "所有文件"
ofn.lpstrFile = Space(254)
ofn.nMaxFile = 255
ofn.lpstrFileTitle = Space(254)
ofn.nMaxFileTitle = 255
ofn.lpstrInitialDir = App.Path
ofn.lpstrTitle = "打开文件"
ofn.flags = 6148
rtn = GetOpenFileName(ofn)
If rtn = 1 Then
Filename.Text = ofn.lpstrFile
Else
Filename.Text = "Cancel Was Pressed"
End If