Diqing Tibetan Prefecture in Yunnan province is a multi-ethnic, multi-religious area. During the long historical process, people with different ethnic identities and religious beliefs have lived with each other and constituted a pluralistic society with difference and integration on the basis of a shared life. Through empirical research on the generative mechanism of the pluralistic society in Diqing, this paper tries to reveal its deep root as well as its significance for today's social governance of borderlands. The case study of Diqing can also help us reflect on "ethnic group", "nationality", "borderland" and other traditional concepts so as to deepen our understanding of FEI Hsiao-tung's theory of "the unity in diversity of Chinese nationalities".