Numerical simulation and deposited experiment of MAG welding are carried out on the conditions of Electro-Magnetic Stirring (EMS) in this paper. Based on the research of EMS welding arc action, a simple EMS-MAG welding Gaussian distribution model using whole heat flux density is established, which MAG welding arc and droplet transfer are regarded as one integrated system. The important additional magnetic field parameter in EMS-MAG surfacing deposited welding is considered in this model. The computer-aided arc measurement system is used to analyze the effects of additional magnetic field in MAG welding. Effects of excitation current on welding penetration and width are analyzed by deposited experiments. Many deposited experiments are used to adjust model parameters and verify the simulation results. By defining key parameter and optimizing the model on the basis of experimental data, it can improve the simulation accuracy effectively. The results show that the established Gaussian distribution model can be used to simulate EMS-MAG welding process.