Abstract: Abstract：In order to enhance the effectiveness of floating debris management in the reservoir area of hydro-power projects, we constructed a multivariate co-governance evolution game model incorporating upstream and downstream clearing points and regulators.We also analyzed the key factors required to achieve the collaborative strategy's equilibrium and combined this with the real situation of clearing debris in the Three Gorges Reservoir area.In addition, we used system dynamics to simulate and optimize the game, revealing the evolution of the strategy for floating debris management.The study revealed that: (1) The improvement of the willingness of cross-border cooperation between upstream and downstream drifting points could alleviate the pressure of government supervision, and indirectly promoted the achievement of a balanced governance of drifting point cooperation.Simultaneously, the changes in their willingness to cooperate were synchronized, and the willingness of the downstream clearing points in the basin to manage the drifting debris was more influenced by the behavioral choices of the upstream points.(2) The local government could keep the upstream and downstream clearing points from becoming local interest conflicts by enforcing strict rules for rewards and punishments and ensuringthat everyone who worked together could get a fair share of the benefits.This was based on a thorough analysis of clearing capacity and other factors.(3) Reasonable clearing capital input and a differentiated subsidy strategy from the project owner could effectively resolve the mutual blame between the government and the enterprise and could promote the cooperative governance of the clearing points.(4) Common interests of upstream and downstream clearing points might enhance the sense of trust among each other, which was a driving force to reach cross-border cooperative governance.