The responsibility system of outsourcing team plays an increasingly important role in the management of letters and visits at the grassroots level, but the full display of its effect requires local governments to implement reasonable incentives and adjust the behavior preferences of grassroots outsourcing teams through strategic choices, so as to achieve a balanced path of the optimal allocation of letters and visits resources among local governments, petitioners and grassroots outsourcing teams. This paper builds an evolutionary game model of heterogeneous preference of the outsourcing team, and analyses the interactive strategy behavior of local government, petitioners and grassroots outsourcing team, and its possible replication of dynamic and steadystate equilibrium results, and studies the influence of the preference difference of the outsourcing team through the simulation of action strategy. The results show that under the established agreement cost and petitioner discount cost, the flow of local government subsidies can determine the behavior preference of grassroots outsourcing teams, which leads to different equilibrium results. Based on this, this paper puts forward some policy suggestions to optimize the behavior of the outsourcing team.