你可以去学习vba的知识操作word
Dim app As New MSWord.Application
try
Dim fileName = "d:\test.doc"
Dim doc = app.Documents.Open(fileName)
doc.Protect (Password:="123456", NoReset:=False, Type:= _
MsWord.WdProtectionType.wdAllowOnlyReading, UseIRM:=False, EnforceStyleLock:=False)
app.Documents.save
catch ex As exception
msgbox(ex.message)
finally
app.Quit
End try