虚拟按键Enter  
Application.SendKeys "{ENTER}"

**在工作表的任意单元格中输入完成后，自动每两个字符强制换行**  
Private Sub Worksheet_Change(ByVal Target As Range)  
Dim str1, str2  
If Target.Count = 1 Then  
str1 = Target.Value  
For x = 1 To Len(str1) Step 2  
If str2 = "" Then  
str2 = Mid(str1, x, 2)  
Else  
str2 = str2 & Chr(13) & Mid(str1, x, 2)  
End If  
Next x  
Application.EnableEvents = False  
Target.Value = str2  
Application.EnableEvents = True  
End If  
End Sub

**如果你只需要前面两个字符换行，后面的不换行，代码修改如下**  
Private Sub Worksheet_Change(ByVal Target As Range)  
Dim str1  
If Target.Count = 1 Then  
str1 = Target.Value  
str1 = Left(str1, 2) & Chr(10) & Mid(str1, 3, Len(str1))  
Application.EnableEvents = False  
Target.Value = str1  
Application.EnableEvents = True  
End If  
End Sub