Abstract: In order to more accurately evaluate the safety of pontoon equipment under surface crack defects, the effects of crack shape ratio and inclination angle on the stress intensity factor at the crack tip were studied.Firstly, the crack model and finite element method were analyzed, and then the method was verified by finite element model. Finally, the stress intensity factor of the crack tip with different shape ratios and inclination angles was calculated, and its variation law was analyzed.The results show that when the crack length is constant, increasing the shape ratio can reduce the stress intensity factor of the crack front, which has a greater impact; when the shape ratio is constant, the stress intensity factor of the plane crack front perpendicular to the axial load is largest.