Buddhism of the south of the Changjiang River plays a very important role in expanding Chinese Buddhism to foreign countries, the most outstanding and typical role among them is the effect of Buddhism of the South of the Changjiang River on Japanese Buddhism. The formation and development of Japanese Buddhism have three important stages, in these stages, the formation of Japanese Buddhism Sect, the reform of religious theory and religious doctrine, the rise of new sects and so on are all closely related to Buddhism of the south of the Changjiang River.