Abstract: To reveal the influence degree of the water conservancy project construction on water environment,this paper improves water conservancy project construction project investment decision-making,considers the natural conditions and social economic impact on the water environmental benefits on the basis of 10 water environmental benefits related indexes. Based on two-level fuzzy comprehensive evaluation method,China’s water supply project in Gansu Province comprehensive evaluation is constructed. The entropy method is used to determine the index weight,and three-criterion layer weight distribution schemes are designed by considering the importance of ecological environment and engineering benefit. The fuzzy calculation results show that the water environmental benefit level of tao water supply project is good and its benefit is significant. The benefits are particularly significant in terms of water supply and population health. The above results objectively reflect the water environmental benefits of Yintao Water Supply Project,and verify the validity of the research method and the rationality of the evaluation model,which can be used for reference in engineering practice.