In order to improve the reliability of the Y-seal for the piston rod of the hydraulic cylinder,the sealing characteristics of the Y-seal in the state of dynamic and static seal were studied.Through finite element analysis,the stress,deformation and contact pressure distribution of Y-shaped seal under different working conditions were studied.According to the principle of hydraulic reciprocating seal,the changing trend of the leakage of piston rod seal in reciprocating stroke under different media pressure was studied.The results show that the Y-shaped seal has weak resistant ability against fluid pressure under installation condition.With the increase of the medium pressure,the sealing performance index of the Y-shaped seal under static sealing state and the net amount of flow back of Y-shaped seal under dynamic sealing state decrease,and the ability to prevent leakage decreases.Under high pressure condition,the anti extrusion ability of Y-shaped seal is reduced,and the root is squeezed into the seal gap,which will cause bite and lead to seal system failure.Aimed at the bite problem of the Y-shaped seal,the root chamfering method was used to optimize the structure.A response surface model was established using the central design method to optimize the Y-shaped seal by taking the leakage as the objective function.The sealing performances of the optimized Y-seal under dynamic and static seal conditions are improved,the wear speed and the risk of being bitten are reduced,and the reliability of Y-seal is improved.