Abstract: According to the characteristic of the water environment impacts, and combined with the engineering characteristic water-shed scale and functional requirements, the criterion of the evaluation levels in the water environment impact assessment in water conservancy and hydropower project was put forward, which was checked in different types and scales of hydropower projects. The results showed that the evaluation levels recommended by the criterion in the water environment impact assessment conformed to the actual requirements. The research could provide reference for effectively applying technical guidelines in surface water environmental impact assessment.