The Dunhuang manuscripts are a cache of important religious and secular documents discovered in the Mogao Caves of Dunhuang, China, in the early 20th century. Dating from the 5th to early 11th centuries, the manuscripts include works ranging from history and mathematics to folk songs and dance. Most of the religious manuscripts are Buddhist, but other religions including Daoism, Nestorian Christianity and Manichaeism are also represented. In this paper, I have discussed about the catholicity of Dunhuang Buddhism contained in Dunhuang manuscripts from four aspects, i.e. Miao zhen zan in the Guiyijun period, school of the Dunhuang temple, Dunhuang vulgar literature texts, the religious manuscripts except Buddhism, namely Daoism, Nestorian Christianity and Manichaeism. Finally, I have discussed about the cause and background of the formation of Dunhuang Buddhism’s catholicity.