Abstract: The main welding deformation of railway carriage side-wall was welded buckling distortion, which was simulated by thermal elastic-plastic finite element method with analysis in several selected areas including continuous welds, plug welds and intermittent welds.The results show that the plug welding and intermittent welding are the main reason that induce bucking distortion of side-wall, in which transverse stiffeners and longitudinal stiffeners are welded on the side-wall.The critical bucking load decreases obviously and the bucking distortion increases on the plate with a free boundary.The measured results of bucking distortion are in agreement with the simulation results.Thus, a complete set of instruction can be received for the real processing.