Abstract: To solve the limitation about deposition rate and welding current can not be decoupled of the traditional micro-plasma arc welding, double-electrode micro plasma arc welding is proposed.The article added a bypass current into the filler wire to make a bypass arc is appeared between the wire and the tungsten. Though this method to realize the decoupling of the heat of melting base material and the heat of melting wire. Thus, the melting speed of the filler wire is increased while the current of melting base material keeps stable.The experimental study was carried out on the deposition rate, the heat input of the base metal and the weld formation quality of the double-electrode micro plasma arc welding. The double-electrode micro plasma arc welding not only maintains the advantages of the conventional micro plasma arc welding, but also improves the deposition rate and reduces the heat input of the base metal; When the other welding parameters remain unchanged, the weld penetration and dilution rate decrease and the forming coefficient increases with the increase of the bypass current.