In order to explore the relationship between the performance index of VL seal and the parameters such as friction and deformation of seal in practical use,the life of VL seal was obtained through the test,and then several groups of VL seal life tests were designed to study the leakage of seal under different life nodes.The effect of inner diameter,cross-sectional profile change,wear mass,friction and surface roughness of lip on the leakage rate were analyzed.The results show that during the life test of VL seal,the leakage rate increases first,then stabilizes for a period of time,and then continues to increase.There is a positive correlation between the change of inner diameter,the change degree of cross-section profile and the wear mass and leakage rate.There is no direct relationship between the change of friction and the change of surface roughness of the lip and the leakage rate.