Abstract: In order to improve the sealing performance of diaphragm pump cylinder pistons, taking the piston V-ring of a diaphragm pump as the research object and based on the orthogonal test method, the V-ring with different structural parameters was simulated using the ANSYS Workbench software. Using the maximum Von Mises stress and maximum contact pressure as evaluation indexes, the primary and secondary structural parameters influencing the value of the indexes were discussed, and the V-ring structure was optimized. The results show that the main factors affecting the maximum Von Mises stress are the outer chamfer and inner length of the lip. The larger the outer chamfer is, the greater the maximum Von Mises stress will be, and too large or small inner length will lead to the increase of the maximum Von Mises stress. The main factors affecting the maximum contact pressure are the outer chamfer, inner angle and outer length of the lip. The maximum contact pressure increases with the increase of outer chamfer, but it decreases with the increase of the inner angle and the outer length. After optimization, the maximum contact pressure of the V-ring is reduced by 6%, still meeting the sealing requirement, and the maximum Von Mises stress is reduced by 28%, significantly improving the sealing performance.