Taking the vane seal of hydraulic swing cylinder as the research object,based on the theory of fracture mechanics,the prediction formula of the vane seal fatigue life was established.The Mooney-Rivlin constitutive model was used to characterize the mechanical behavior of the seal material,and ABAQUS was used to analyze the sealing structure.The effects of precompression rate and working oil pressure on the fatigue life of vane seals were studied.The fatigue life prediction formula was used to predict the life value of the dangerous section.The research results show that the most vulnerable position of the vane seal is located at the low pressure side near the chamfer of the blade groove.At the precompression rate of 10% to 20%,the fatigue life increases first and then decreases,and reaches the peak value at the compression rate of 12%.The working oil pressure has the greatest influence on seal failure and fatigue life.When the working oil pressure reaches 10 MPa,the fatigue life decreases rapidly.The correctness of the theoretical analysis is verified by testing the fatigue fracture position of the vane seal of the prototype.It provides a theoretical method for the prediction of the fatigue life of vane seal of hydraulic rotary vane actuator.