Abstract: To achieve the heat and mass transfer decoupling proposed bypass coupling arc welding process (Arcing-wire PAW). First introduced the bypass coupling arc welding process-Arcing-wire PAW principle and system components, data synchronize acquisition systems and the high-speed cameras were used to record the changes of droplet transfer, combined with changes in electrical signals and droplet transfer behavior of different welding parameters on droplet transfer. The results showed that the changes of MIG wire feed speed and MIG current all change the wire melting equilibrium position, so that the droplet transition state and the frequency changes, in addition, the changes in the height of the vertical wire can make full use of the heat bath to achieve stable and rapid transition. Because of heat and mass transfer can be controlled separately and arc shape is elongated in the direction of welding, ensuring high-speed welding and weld stability of the welding process.