隨著二十世紀初中國四大史料群的出現，日本逐步建立起作為中國史研究之輔助學科的中國古文書學。這一學科可細分為以文書調查、蒐集、整理等為內容的基礎古文書學，和以樣式論、形態論、機能論、流傳論為組成部分的應用古文書學。以唐代告身研究為例，日本的中國古文書學研究經歷了萌芽期、發展期與成熟期，在各個研究層面都出現了出色的學術成果。而且，相關研究並非囿於古文書學研究本身，更以告身為基礎，拓展至唐令復原、官僚行政機制以及唐日交流史（含法律移植）、日本古代史等領域。如上種種，皆可為中國建立自己的中國古文書學提供借鑑。

With the unprecedented discovery of the four types of historical materials in the early 20th century, two branches of the diplomatics on Chinese ancient documents in Japan have been developed. The fundamental one is to invest, collect and collate documents. And the second one, applied diplomatics, is consist of the studies of materials’ form, pattern, function, and circulation. Take the study of gaoshen of Tang Dynasty in Japan for example. Its scholarship shows that the diplomatics in Japan has gone through striking development. Scholars who study gaoshen also referred to the research on remnants of Tang Statutes, bureaucracy in Tang, and cultural and legal exchange between Tang and ancient Japan. Japanese experience on studying diplomatics is referential when China wants to establish its own diplomatics.