I can do it now I can use FindWindow,GetWindow and SendMessage to send message to a notepad app,just like this: hWnd1 = FindWindow(null, "Untitled - Notepad"); hWnd2 = GetWindow(hWnd1, GW_CHILD); sText =this.textBox1.Text; SendMessage (hWnd2, WM_SETTEXT,sText.Length, sText); but I don't know how to excute a word app's dictate by another app,help me please ,thank you! you are welcome to visit my blog