Objective: The fatigue strength of a new type of vertical retort under the cyclic load of heat engine was studied, especially the residual fatigue life of the pot body after the crack appeared and the factors affecting the fatigue crack propagation of the germicidal pot. Methods: The mechanical characteristics of retort under sterilization and three kinds of cyclic loads were analyzed by Workbench, the design fatigue life of the retort under three alternating stresses was studied based on the S-N curve. The effect of the initial crack size, pressure and temperature on the stress strength factor and residual fatigue life of the crack retort were studied based on fracture mechanics. Results: The design fatigue life of this type of vertical retort was calculated to be 5×10⁵ times, which meet the design requirements, and has a certain safety margin. Based on the fracture mechanics analysis, the crack size life curve of the sterilization retort was obtained, and the residual life of the sterilization retort with defects was predicted, which had certain innovation. Conclusion: Attention should be paid to the occurrence and propagation of cracks in the pot during use. The strength analysis and life prediction analysis of crack defects in the sterilization retort can be carried out according to the method proposed in this paper and experiment.