Abstract: Abstract: Scientific and reasonable evaluation of project construction effectiveness plays an important role in the follow-up project management. However, the post-assessment of project construction effectiveness is a multi-complex system involved in many certain and uncertain factors, with complicated nonlinear relationship between evaluation indicators and grade standards, which should be considered in post-assessment. In this study, a set pair analysis model based on game theory was developed. In the model, the weights of evaluation indicators were obtained by game theory, and then the connection degree of the single index was calculated in the support of certain and uncertain analysis method of set pair theory. Then, the comprehensive connection degree of the object was obtained based on the model. So the evaluation grades and the transformation trend between grades of objects were confirmed. Based on the above analysis, the set pair situation was introduced to analyze the coordination among the subsystems, clarify the underlying causes of transformation trend and evaluate the sustainable development level of the project. The model was applied to the post-assessment of the rural drinking water safety project construction effectiveness of Hunan Province, and the results were compared with that from sudden change evaluation method. The results showed: 1) Project completion rate, qualification rate of project, water fee profit, completion rate of resolving rural drinking water difficulty, rural tap-water benefit rate, water quality and water environment protection of water functional zone were the main factors affecting rural drinking water safety in Hunan; Among these factors, water fee profit, rural tap-water benefit rate, water quality and water environment protection of water functional zone were key limiting factors of the project benefits; 2) Three areas (Hengyang, Chenzhou and Yongzhou) had "excellent" rural drinking water safety level, while Changde, Yiyang and Loudi had "general level", and the others in "well" level; 3) The five indexes in project management subsystem were at levelⅠor levelⅡin all the areas, indicating that the governors of Hunan Province have paid much attention to the management of the people's livelihood project in recent years; However, the level of the indicators in socioeconomic performance subsystem and ecologic environment response subsystem were generally poor and the protection of ecological environment haven't been done well; 4) The three subsystems of the rural drinking water safety system in Changsha and Huaihua were in strong coordination state, so the project was in a high sustainable development level; The coordination level of the three subsystems in Loudi was general, thus the sustainable development level was not high; The three subsystems in Zhuzhou was out of coordination, indicating worrying sustainable development; The coordination degree of the subsystems in Hengyang and Chenzhou was almost uncoordinated, making the project sustainable development condition poor; The subsystems were in harmony in other cities, so the follow-up benefit of the projects were relatively stable. The results above illustrated that the proposed method are reliable, can reflect more comprehensive information than the sudden change evaluation method. Therefore, the study can provide a reliable method for the decision-making and management of the similar projects or follow-up projects.