OK, try this then ..
You can change the number of pages in each small file where shown
Also you need to change it to save in your own path, again where shown
Sub SplitBigDoc()
Dim BigDoc As Document, NewDoc As Document
Dim SeqNo As Integer
Set BigDoc = ActiveDocument
SeqNo = 0
Application.ScreenUpdating = False
While Len(BigDoc.Content.Text) > 1
With Selection
.GoTo wdGoToPage, wdGoToAbsolute, 200 ' <=== Number of Pages here
.HomeKey wdStory, True
If Selection.Information(wdActiveEndPageNumber) <> 200 Then
BigDoc.Content.Select
.Cut
Set NewDoc = Documents.Add
With NewDoc
.Content.Paste
SeqNo = SeqNo + 1
.SaveAs "Part" & SeqNo & ".doc" ' <=== Full Path and Name here
.Close
End With
End With
Wend
Application.ScreenUpdating = True
Set NewDoc = Nothing
Set BigDoc = Nothing
End Sub