Abstract: The interaction between MIG arc and plasma flow in plasma-MIG hybrid welding was analyzed. The heat source model of the hybrid welding was revised in combination with the observation of the shape of the hybrid arcs. Considering the repulsion between the reverse plasma flow and the MIG current in hybrid welding, the hybrid welding process with the introduction of arc deflection angle was simulated and calculated, the influence of the deflection angle on the temperature field was analyzed, and the calculation results were compared with the experimental measurement. The comparison results showed that the calculation results of the heat source model formula after introducing the arc deflection angle could better describe the physical process of hybrid welding, which had a certain practical application value for optimizing its welding process parameters.