你可以使用API函数FindWindow和PostMessage去寻找指定的窗口，并关闭它。下面的例子教给你怎样找到并关掉一个Caption为“Caluclator”的程序。

Dim winHwnd As Long

Dim RetVal As Long

winHwnd = FindWindow(vbNullString, "Calculator")

Debug.Print winHwnd

If winHwnd <> 0 Then

RetVal = PostMessage(winHwnd, WM_CLOSE, 0&, 0&)

If RetVal = 0 Then

MsgBox "置入消息错误！"

End If

Else

MsgBox "Calculator没有打开！"

End If

为了让以上的代码工作，你必须在模块文件中什么以下API函数：

Declare Function FindWindow Lib "user32" Alias _

"FindWindowA" (ByVal lpClassName As String, _

ByVal lpWindowName As String) As Long

Declare Function PostMessage Lib "user32" Alias _

"PostMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, _

ByVal wParam As Long, lParam As Any) As Long

Public Const WM_CLOSE = &H10