The excessive behavior of the government is a common phenomenon in the practice of PPP projects such as transportation, municipal engineering and environmental governance. Analyzing the excessive behaviors of the government in PPP projects is very important to improve project performance and success. Based on the field dynamic theory, the demand of government and the external environment participating in PPP are the important reasons for excessive behavior. Through literature analysis, 14 government demands and 10 environmental factors that influence the government's excessive behavior are identified, and a hypothesis model of the influencing path of government's excessive behavior is constructed. 166 valid data are collected through a questionnaire survey. Carrying out factor analysis, hypothesis, and path test, the main findings are as follows: Government’s demands are divided into the demand of satisfying public activities, self-interest, responsibility, and relieving financial pressure; External environmental factors are divided into social conditions, department mechanism, and project information; The demand for responsibility plays a restraining role, while the other types of demand are opposite, and these demands play an intermediary role in the impact path of external environment on excessive behavior; Among the environmental factors, only the lack of project information has a direct influence on the government excessive behavior; In the feasibility subsidy project, the risk of excessive behavior is high, especially for transportation projects with certain toll nature. The study provides suggestions for reducing the risk of government behavior in PPP projects.

政府的过度行为是交通、市政工程、环境治理等PPP项目实践中的普遍现象。分析政府在PPP项目中的过度行为，对于提高项目绩效和成功率非常重要。基于场动力理论，参与PPP的政府需求和外部环境是过度行为的重要原因。通过文献分析，识别出影响政府过度行为的14项政府需求和10个环境因素，构建了政府过度行为影响路径假设模型。通过问卷调查收集到166项有效数据。进行因素分析、假设和路径检验，主要研究结果如下：政府需求分为满足公共活动需求、自身利益需求、责任需求和缓解财政压力需求；外部环境因素分为社会条件、部门机制、项目信息；责任需求起约束作用，其他类型需求则相反，这些需求在外部环境对过度行为的影响路径中起中介作用；在环境因素中，只有项目信息的缺乏对政府过度行为有直接影响；在可行性补贴项目中，过度行为的风险较高，尤其是具有一定收费性质的交通项目。