Abstract: Institution is the guarantee of the rapid development of sharing finance. Based on the concepts of formal and informal institution of institutional economics to the institution evolution model， the process of institutional construction and integration of sharing finance is divided into three stages: the first stage is incentive formal institution and mixed informal institution， with relatively gentle institutional conflicts; the second stage is constrained formal institution and constantly improving informal institution; the third stage is characterized by the unification and integration of formal and informal institutions. In order to achieve the goal of the integration of sharing finance institution， regulators should take formal institution as the core， optimize policy supply and power distribution; sharing finance enterprises should focus on informal institution， strengthen self-discipline consciousness and cooperation ability; at the same time， they should combine with other market roles to form a linkage system of institutional integration.

Key words: sharing finance, formal institution, informal institution, institutional integration