Abstract: A novel and highly effective consumable double electrode gas metal arc welding method was introduced. However, the coupled arc and welding process were very unstable in practice and led to serious defects in the weld bead. A new double closed-loop control plan was proposed and simulated after analysis of the relationship between welding parameters to control the bypass arc through the bypass feed speed and control the motherboard current through the bypass current. Then the experiments with this plan were carried out using rapid prototyping and Matlab/Simulink. The results show that the stable welding process and motherboard current could be achieved,and the welds with less defects and good appearance were also obtained.