为解决安全评估工作中存在的信息瞒报与误报等违规串谋行为，引入机制设计理论，在信息不对称条件下，针对安全状态类型和安全信号类型的不确定性，构建政府、港口企业及评估机构三方契约设计模型，并深入分析安全状态类型对契约参数的影响以及各主体最优策略选择.研究表明：在一定条件下，政府通过对港口企业信息租金、吞吐量和港口规费等契约参数的调整，可以有效抑制串谋发起动机并提高安全状态；在既定监管力度下，安全状态存在一个阈值，低于阈值，需通过“激励+惩罚”双重机制实现防串谋，高于阈值，只需通过“惩罚”机制即可实现防串谋.

In order to solve the illegal collusion such as information concealment and false reporting in security assessment, the mechanism design theory was introduced to build a tripartite contract design model for government, port enterprises and assessment institutions under the condition of information asymmetry and in view of the uncertainty of security state type and security signal type, and the impact of security state types on contract parameters and the optimal policy choice of each subject were also analyzed. The results shows that under certain conditions, the government can effectively restrain collusion and improve the security state by adjusting the contract parameters such as information rent, throughput and port fees of port enterprises. Under the established supervision, there is a threshold for the security state, below the threshold, it is necessary to achieve the anti-collusion through the dual mechanism of “incentive + punishment”, and above the threshold, only the “punishment” mechanism is required to achieve anti-collusion.