In order to accurately evaluate the impact of tail water diversion projects on the society in the regions along Eastern Route Project of South-to-North Water Diversion, the profits and losses of social impact of the tail water diversion projects are investigated from the following four aspects: living quality, heath, psychological recognition and environmental consciousness of the residents. By use of the evaluation methods for the profits and losses of social impact such as the contingent valuation method, disease cost method, market value method and cost method as well as the sociological methods such as questionnaire survey, the evaluation model for the profits and losses of social impact of tail water diversion projects is established. Based on the calculation of their influences on the living quality of the residents, the monetization evaluation of the social impact of tail water diversion projects is realized. The empirical results show that the total profits of the social impact of the living quality of the residents along Eastern Route Project of South-to-North Water Diversion induced by the tail water diversion projects are 8. 5056016 billion RMB Yuan, and the social benefits are significant. It may provide reference for the social impact evaluation of water conservancy projects and support for the governmental decision-making of environmental treatment projects such as tail water diversion.