Abstract: In this paper, from basic theories of fracture mechanics, we have introduced the idea of equivalent energy release rate, constructed a model of fatigue propagation rate of surface cracks and derived a series of equations. After studying bending fatigue propagation laws of surface cracks in sheet and-shaft specimens, we have set up a characteristic method of predicting the fatigue life of elements with surface cracks by means of experimental results of general through-crack specimens of the same material.