The active risk management behaviors of core stakeholders in the operation process of water diversion PPP(public-private partnership) projects can reduce the probability of project risk occurrence. From the perspective of risk management, through the analysis of stakeholder relationship of water diversion PPP projects, the behavioral decision-making evolutionary game model of government subject and social capital (project company) in the risk management process of water diversion PPP projects during the operation period is constructed, and the dynamic evolution process is analyzed by MATLAB. The results show that the factors influencing the choice strategy of evolutionary stable behaviors include the cost actively managed by both the government and social capital, the loss caused by risk events such as water pollution and loss distribution coefficient, feasibility gap subsidy and reward. In order to promote effective risk management in the operation process of water diversion projects, it is suggested to strengthen the risk management capacity building of both the government and the social capital, implement the responsibility sharing mechanism, improve the supervision mechanism and optimize the reward and punishment mechanism.