Try
Dim fileName = pth & dr("纪要文件名称") & ".doc"
Dim doc = app.Documents.Open(fileName)
doc.Saved = True
app.Documents(fileName).ExportAsFixedFormat(pth & dr("纪要文件名称") & ".pdf", MSWord.WdExportFormat.wdExportFormatPDF)
app.Quit
Catch ex As Exception
msgbox(ex.message)
app.Quit
End