Dunhuang Studies in Japan originated from Otani Kozui expedition team's first expedition that kicked off in 1902.The relationship between Otani Kozui and Dunhuang Studies in Japan could be summarized into three aspects.Firstly，Otani Kozui，as the planner and organizer for three expeditions to Central Asia，and his expedition team's “initiative activities” inaugurated Dunhuang Studies in Japan.This not only marks the starting point of the Japanese field research on Dunhuang，but also “equates” Japan to Britain and France in the field of exploring and looting Dunhuang and Tulufan relics，hereby laid the foundation for the “three-powers” situation in the early period of Dunhuang Studies worldwidely.Secondly，with various gathering methods the “Otani Collection” came into being，which provides an enormous wealthy sum of manuscripts，being used as Japan's largest scale concentration of excavated cultural relics for Dunhuang Studies.Thereby the early Dunhuang Studies in Japan developed from the initial stage，when acquiring information and making introduction composed the main work and only preliminary studies were conducted referring photos and documents reproduced in Britain or France，to the new stage，when in depth and systemic studies were conducted with reference to the excavated objects.Thirdly，Luo Zhenyu and Wang Guowei were stimulated to visit Japan and were able to make use of the collection for studies，and then had profound communication and interactions with the Dunhuang Studies scholars mainly from the College of Letters，Japan Kyoto Imperial University，thus jointly created the glory of early East Asian Dunhuang Studies，and led the world Dunhuang Studies into a new level.