A certain type main generator frame used in railway vehicles is taken as a research objective. The finite element simulation analysis of the frame is carried out by ABAQUS. The static strength is evaluated according to the actual working condition and design requirements;reference to the standards of IIW and EN15085,the fatigue strength and stress factor of the dangerous welds in the generator frame are calculated by the hot spot stress method and the equivalent structural stress method respectively and the results are compared.The results show that: under limited conditions,the maximum Mises stress of the generator frame is less than the yield strength of the base material,so the frame meets the static strength requirement;under the impact and stop conditions,the maximum stress change range of hot spot stress of the dangerous welds in the generator frame is less than the cut-off fatigue limit of the corresponding S-N curve,and the fatigue strength of the frame meets the design requirements. The structural stress at the dangerous weld toe is extracted by FE-SAFE,and the fatigue life of the dangerous weld obtained by the equivalent structural stress method can also meet the design requirements. By comparing the stress factors obtained by the two methods,it is concluded that the equivalent structural stress method can predict the fatigue life of welded structures more efficiently and accurately when the welding structure is complex.