Abstract: Agricultural reclamation is an agricultural management mode established in special historical conditions, special development periods and specific regions. With the gradual improvement of China's socialist market economic system, the management of agricultural reclamation areas is facing a series of institutional problems. The report of the Nineteenth National Congress of the Communist Party of China pointed out that we should build a pattern of social governance of co-construction, co-governance and sharing, and strengthen the construction of social governance system. The governance model of Frontier multi-ethnic farming and reclamation areas involves not only economic and social benefits, but also harmony, stability and national security. Starting from the current problems and significance of the governance of reclamation areas, this paper explains the connotation and internal logic of co-construction, co-governance and sharing. Taking Xishuangbanna reclamation area as an empirical study, this paper analyses the current problems of system dilemma, management dilemma and individual identity dilemma in reclamation areas, and explores the governance mode of "government+market+society" in multi-ethnic border reclamation areas from the perspective of Co-construction and co-governance.