Abstract: Indirect reciprocity mechanism is attempted to introduced to analyze decision-making process of public and private sectors,and study the causes and coping mechanisms of opportunistic behaviors,based on evolutionary game model in this paper. The results show that the earnings of opportunistic behavior is the key factor to result in opportunistic behaviors,based on indirect reciprocity. The punishment mechanism can't prevent opportunistic behaviors; The greater future cooperation earnings and the reputation coefficient are,the more the private sector tend to take reciprocity behavior,which result in Pareto optimal. Based on the above findings,the government is suggested to propose the incentive policy to expand the PPP market,and to establish the reputation and punishment mechanism to prevent opportunistic behaviors.