The strength of laser overlap laser welding joint of the column and the side wall of stainless steel railway vehicle body is higher than that of resistant spot welding joint,the frature forms of the two welding methods are different in the fatigue test. From a mechanical point of view,this may be related to the different stress distribution and the stress concentration of the two joints. And the stress concentration is the main factor causing the fatigue damage of welded joints. Therefore,based on the ABAQUS finite element analysis software,the stress distribution of the two kinds of joints under different applied loads is numerically analyzed,the stress concentration factor is calculated,and the initiation and propagation of fatigue cracks are predicted. The results show that the stress concentration factor of resistance spot welded joint is 4.42 times higher than that of laser welded joints,and 2.76 times higher than that of laser welded joints on one side of the column. The fatigue crack initiation position is at the maximum stress concentration,consistent with the simulation results.