Abstract: Bogie is an important part of high-speed electric multiple units (EMU), the welding quality of bogie side beam is directly related to the smoothness and safety of the railway vehicle. In order to study the effect of welding heat input on the welding residual deformation of bogie side beam, the curve T-joint model was extracted from the bogie side beam. Taking welding speed, welding current and welding voltage of gas metal arc welding (GMAW) as research objects, the surrogate model was established based on the thermal-mechanical coupling simulation analysis method and orthogonal design of experimental (DOE) method with interaction, and the optimal combination of process parameters is obtained based on particle swarm optimization (PSO) algorithm. The influence of above parameters on welding heat input and welding residual deformation is further discussed using range analysis and analysis of variance (ANOVA). Applying the optimal welding process parameters and production process parameters to curve T-joint model and the bogie side beam, respectively, the angular deformation result of the curve T-joint model using the optimal process parameters is 5.04% better than the result using the production parameters, and the welding residual deformation of the upper and lower cover plates of the side beam can be guaranteed to meet the requirement of flatness 1 mm without post-welding treatment.