Abstract: In terms of main effective factors of the damage issue of the top seal of high-head valves, three kinds of material formulas are proposed. A test method with the same test condition for all test specimens was designed. The underwater stone method was employed to carry out the abrasion resistance performance test. A 1:1 scale slice test device was created and test specimens of different types of top seals were made. The test study on the deformation of top seals under fixing and different water heads was carried out. The study indicated that the damage feature of the top seal surface shows the wave style, and the larger the top seal hardness is, the smoother is the surface abrasion. Formula No.2 is relatively better. The deformation of the top seal increases linearly with the increase of the installation load and the water head. The top seal of semicircle head type is relatively better among all the top seals involved in the test. As the deformation of the top seal is large under high water head, some gap between the top seal and the breast wall is recommended when the top seal is installed to reduce its compression deformation and stress.