1、打开Word文件的 VBA编辑器，快捷键 Alt+F11，右击【ThisDocument】-》 【插入模块】;
2、双击刚才插入的【模块1】，添加如下代码：
Private Function SaveAsFile(ByVal fileFormat As String)

Dim strDocName As String
Dim intPos As Integer
'Find position of extension in filename
strDocName = ActiveDocument.Name
intPos = InStrRev(strDocName, ".")
If intPos = 0 Then
'If the document has not yet been saved
'Ask the user to provide a filename
strDocName = InputBox("Please enter the name of your document.")
Else
'Strip off extension
strDocName = Left(strDocName, intPos - 1)
strDocName = strDocName & fileFormat
End If
'Save file with new extension
ActiveDocument.SaveAs fileName:=strDocName, fileFormat:=wdFormatText
'Close active document
ActiveDocument.Close SaveChanges:=wdSaveChanges, OriginalFormat:=wdOriginalDocumentFormat

End Function
3、保存代码及文件，且关闭word并重新打开，重新打开点击【选项】-》 【启用此内容】