Abstract: The influence of different current and pulse frequency of M-arc on the droplet transfer behavior was verified using a welding system with Tri-arc DE welding and a high speed camera and waveform synchronization acquisition system. The results show that the main reason for the change of the droplet transfer behavior is the force produced by M arc. Then, there is a corresponding relationship between the droplet transfer behavior and the change of the M-arc current. With the increase of the M-arc current, the droplet transfer behavior changed from short circuit transition + jet transition to large drop transitions, jet drop transitions and jet transitions. With the increase of M-arc pulse frequency, the droplet transfer changed several drops per pulse, one drop per pulse, one drop within several pulses. The ideal weld forming pattern is the one-drop one transition phase.