Abstract: The welding induced deformation of stiffened plates is investigated in this paper with the thermal elastic plastic FE method. In order to improve the calculation efficiency, shell elements with section integration are adopted to establish the shell/solid model. Two welding methods are studied respectively in this paper, and several conclusions are drawn after comparing the calculation results. It is observed that simultaneous welding on two sides of the stiffeners could lead to a better deformation mode of the stiffened plate, which is less significant and shows better symmetry, compared to that of successive welding.