T-type welding is a widely used form of welding. The welding deformation and residual stress in the welding process will affect the integrity and reliability of the structure. In order to offset and compensate the welding deformation,the workpiece is artificially deformed in the direction opposite to the welding deformation. This method is called reverse deformation method,which is one of the most commonly used methods in production. In order to study the effect of reverse deformation on post-weld deformation and residual stress,the multi-layer multi-pass welding deformation and residual stress field of T-joint of S355 steel were numerically simulated based on thermo-elastic-plastic method. The results show that the maximum deformation of T-joint of S355 steel occurs at the web far from the weld,and the Von-Mises equivalent stress is concentrated in the weld zone and heat-affected zone. By applying proper reverse deformation to the web,the welding deformation can be effectively reduced without affecting the peak value of the overall residual stress,thus taking into account the flatness and bearing capacity of the T-joint. The research results in this paper have certain guiding significance for actual welding production.