Abstract: Analyzing the droplet transition path of twin wire welding,the phenomena that front arc and rear arc of twin wire welding deflect to the middle of the two wires are found due to the influence of magneticblow.Based on this phenomenon,the double ellipsoid heat source model is amended and the heat source model of twin wire welding is presented that can have the ideal accuracy testified by actual experiment of temperature sampling.Then,numerical simulations of twin wire welding temperature field for 2219 high strength aluminum alloy sheets were carried out and distribution of welding temperature field were investigated.