Abstract: Fatigue crack propagation rate of metallic materials is an important index of mechanical property, which is employed for assessment of safe service and prediction of fatigue life for metallic materials and their corresponding components with cracks in them. In this paper, based on different stages of fatigue crack propagation of metallic materials, closure effect, influence of stress ratio on fatigue crack propagation and so on, characteristics of different models for fatigue crack propagation rate were compared and analyzed, which would provide reference for selecting appropriate models in safety design and life prediction.