Abstract:A fatigue life model of aeronautic rolling bearing made by M50NiL steel was established with Goodman formula and material PSN curves,based on LundbergPalmgren fatigue life theory (LP theory) and Hertz contact theory,considered the effect of thermomechanical coupling.The model was mostly related to the maximum Hertz contact stress and material coefficients.When solving the stress by the software of ANSY,the thermal load was calculated by using thermoplastic finite element method,and the regularities of loading distributions under the effect of thermomechanical coupling were determined by using the distribution of heat stress as boundary conditions of stress analysis.According to the data above,the fatigue life of the main reducer cylindrical roller bearing of a helicopter under one working condition was evaluated,and the error of the evaluation result was only 1161% compared with the test value.The results show that the evaluation result calculated by this method is securer than the test result,which indicate that the method is a safe and effective evaluation method of fatigue life.