Abstract: Welding deformation can be seen visually, and many methods are used to control welding deformation. Residual stress distribution is complex, and it has a great influence on production. In this research, the design method of welding numerical simulation and experimental method is used to optimize the process parameters. Residual stress distribution of T-joint is obtained by using single factor and multi factor orthogonal test. The results show that when the gap is 2 mm, the macro morphology can meet the requirements. Welding speed is the most significant, followed by wire speed and welding gap. The research is to optimize the welding parameters and reduce the peak value of residual stress by using the method of numerical simulation and experiment. It achieves the purpose of reducing the experiment times and saving the cost.