Abstract: By analyzing the shape of twin wire welding arc and the track of droplets transfer, the phenomena that both fore arc and back arc deflect to the middle of the two arcs was found in the twin wire welding. Based on this, the double ellipsoid heat source model was modified, and a heat source model to calculate the twin wire welding temperature field was put forward. This model was testified by actual experiment of temperature sampling. Then, the evolution regularities of longitudinal and transverse stress for 2219 Al-alloy were investigated under the condition of twin wire welding.