[Objective] The overall ecological benefits achieved by the Danjiangkou reservoir area and upstream water and soil conservation project ("Danzhi" project) in the second phase of the five-year project (2011-2015) was quantitatively evaluated, in order to provide a reference for decision-making within China's soil and water conservation project and ecological benefit evaluation.[Methods] Based on the grey relational theory, this paper uses a combination of the entropy method and analytic hierarchy process (AHP) to determine the weight of the evaluation index. Based on this, an improved TOPSIS evaluation model was constructed, and the rationality of the results was verified by using "the soil erosion area" index in the project area.[Results] At the beginning of the "Danzhi" project, the various measures had not been perfected, the functions had been relatively lagging behind, and the ecological benefits were relatively low. With the gradual exertion of various functional measures, the ecological benefits of the soil and water conservation had been greatly improved, and the overall ecological benefits at the end of the fifth year have increased by 3.48 times compared with the initial period.[Conclusions] The overall ecological environment in the area of the "Danzhi" project is gradually developing in a benign way, which is consistent with the actual situation in the project area. Based on the improved TOPSIS evaluation model, it has strong applicability and reliability for the benefit evaluation of soil and water conservation project.