In order to investigate the failure mechanism of rotary lip seal,a multi-field coupling model of the rotary lip seal was constructed by comprehensively considering the effects of fluid,asperity,elastic deformation and temperature on the rotary lip seal.A point update strategy was proposed to simulate the wear degradation model of rotating lip seals under mixed lubrication conditions.A fault simulation test was designed,and the test results were compared with the simulation results to verify the effectiveness of the simulation method.The results show that the wear rate of the lip seal is larger at the initial stage,and then tends to be gentle.The contact pressure at the tip of the lip is the largest,and the wear rate is the largest.