Abstract: In hydropower project, the anti-seepage type not only relates to the safety of the project, but also firmly control the engineering investment and schedule. Therefore, choose the right means of anti-seepage type according to the actual conditions is very important. Based on this, the research and design optimization of Yuwa hydropower station's anti-seepage type is proceed on the basis of fully considering the site condition. The main research results are as follows: ①Double loop trial pit water injection method is used to re-check the infiltration parameters of the first layer of cladding, the results show that the permeability coefficient and allow hydraulic gradient value decided based on field pumping and injecting water test are reasonable.②Because of less test data, the allowable hydraulic gradient value decided through the experience of the engineering analogy in early period is conservative, in construction stage, it is changed from 0.07~0.10 to 0.10~0.12 in combination with the results of size distribution testing.③Combined with the adjusted allowable hydraulic gradient value, the anti-seepage type is optimized, the blanket length down to 55m from 80m, which won large economic benefits. The method and thought proposed in this paper can provide certain reference value for similar engineering design.