Subway safety is one of the important part in vehicle design. When lifting the whole vehicle, the axle box lifting lug cooperates complete the lifting function of the bogie with the frame limit stop. During vehicle operation, the fracture of lifting lug will affect the safety of vehicle operation. Firstly, the failure types of the lifting lug are analyzed, and the finite element simulation calculation of the lifting lug structure is carried out according to the vehicle design standard. It is obtained that the lifting lug structure meets the design requirements of static strength and fatigue strength. In order to further analyze the cause of fatigue fracture of the lifting lug, the position of the resistance strain gauge is determined according to the static strength results and fatigue failure position, and the on-line experiment is carried out on the stress condition of the lifting lug structure. Through the analysis of the experimental results, it is concluded that the main cause of fatigue fracture of the lifting lug is resonance. Finally, the lifting lug is optimized from the two aspects of structure and material. The finite element analysis and experimental results show that scheme 1 is the best scheme.