Abstract: The temperature field of single wire and tandem wires narrow gap submerged arc welding were calculated by using the special heat source model. The effectiveness of the simulation results was verified by the experiments. The simulation results show that the temperature field aredifferent between the single wire and tandem wires welding. The temperature field of the tandem welding is dissymmetric with largerweld width and smaller weld penetration on the sidewall. The influence of current fluctuation in the penetration of the sidewall is smaller in the tandem welding. With the same current and voltage,the tandem welding has higher deposition efficiency and a smaller tendency to produce overheated zone.