<p>The welding processes generate residual stress in structures. Finite element methods are widely used to determine residual stresses, but this method has some problems due to the movement of the welding nozzle. In this research, numerical solution based on element-free Galerkin (EFG) method is extended to predict the temperature distribution and residual stresses due to welding. Thermal and mechanical analysis based on thermal-elastoplastic method is done in two stages. To reach the final nodal distribution, the shape and size of the support domain, influence domain size, different weight function and distance between nodes were studied. To validate the results, laser thermometer and the hole-drilling strain-gauge method have been used for the results of temperature field and residual stress, respectively. A good agreement has been obtained between the results of numerical solution and experimental methods, which indicates the accuracy of the presented formulation and the effectiveness of the parameters investigation method. Accordingly, a new application for the thermo-elastoplastic equation based on the EFG method to prediction of the temperature distribution and determination of residual stresses has been presented.</p>