新建一个Excel文档,打开Excel的VB编辑器.
双击Workbook打开代码窗口,粘贴下列代码到Workbook的代码窗口.
保存代码并关闭ExcelVB编辑器.
设置宏安全性为低.
保存关闭Excel文档,重新打开Excel文档即可.

Public Sub MyMacro()
dTime = Now + TimeValue("00:00:01")
Application.OnTime dTime, "ThisWorkbook.MyMacro", , True
With Range("A1")
.Value = Now
.NumberFormat = "yyyy-mm-dd hh:mm:ss"
End With
End Sub

Private Sub Workbook_BeforeClose(Cancel As Boolean)
Application.Quit
End Sub

Private Sub Workbook_Open()
MyMacro
End Sub