The mixed lubrication model of double lip Y-type tie rod seal was established,and the analysis of hydrodynamics,contact mechanics and deformation mechanics was carried out.MatLab software was used to solve the model,and the flow rate,film thickness and contact pressure distribution in the sealing area were obtained.The influence of seal different surface roughness on friction torque and leakage of axial reciprocating double lip Y-shaped seal ring was analyzed.The results show that both lips of the double lip Y-type reciprocating seal are in mixed lubrication state during the sealing process,and the film thickness of the first inner lip is larger than that of the second inner lip.The static contact pressure distribution of the second inner lip is approximately symmetrical,and the maximum contact pressure of the second inner lip is greater than that of the first inner lip,which shows that the second inner lip as the second line of defense for sealing can ensure good sealing effect.The roughness of seal is an important factor affecting the sealing performance,with the increase of surface roughness,the friction force and leakage volume of the linear reciprocating seal increase,and there is a critical roughness that changes the leakage direction.