需要VB API函数：
FindWindow ←寻找窗口列表中第一个符合指定条件的顶级窗口
GetWindowThreadProcessId ←获取与指定窗口关联在一起的一个进程和线程标识符
相关API声明：
FindWindow
↓
Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
GetWindowThreadProcessId
↓
Private Declare Function GetWindowThreadProcessId Lib "user32" (ByVal hwnd As Long, lpdwProcessId As Long)
As Long
需要的控件：Label、Timer
自定义函数：
Dim hwnd As Long
源代码：
Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Private Declare Function GetWindowThreadProcessId Lib "user32" (ByVal hwnd As Long, lpdwProcessId As Long)As Long
Private Sub Timer1_Timer()
Dim hwnd As Long' 储存 FindWindow 函数返回的句柄
hwnd = FindWindow(vbNullString, "Windows Media Player")' 取得进程标识符
'只要把Windows Media Player换成别的程序名称就可了！
If hwnd = 0 Then
Label1.Caption = "未运行"
Else
Label1.Caption = "已运行"
End If
End Sub
下面建议你去下这个API浏览器。比较好用。
http://topic.csdn.net/thttps://files.jxasp.com/image/20040925/17/3408734.html
