In the PPP project, due to the goal inconsistency and information asymmetry of the government department and contractor, the contractor''s opportunistic behavior is common during the whole life cycle. Based on the stochastic evolutionary game theory, this paper constructs a game model with the Moran process to study the evolutionary dynamics of different behavior strategies. The purpose is to explore the favorable conditions for promoting PPP project contractors not to adopt opportunistic behavior strategy. Studies have shown that the occurrence probability of contractor''s opportunistic behavior can be lowered by increasing of the number of contractors or reducing the reporting cost between contractors and increasing the punishment cost of opportunistic behavior. Further, results are verified and management countermeasures are demonstrated with the numerical examples.