Abstract: For the droplet transfer for pulsed metal inert-gas (MIG) welding,a new waveform control method of waveform with median phase was presented.The effect of median current and median time on the droplet transfer was studied.The optimum median current and median time were found by experiment when welding steel using waveform with middle median phase.The experiment result shows that instantaneous short circuit occurs when the median current is small and the median phase has not effect on the droplet transfer when the median current is large,and when the median current is an optimum value,the welding effect is satisfactory.On the basis of defining the median current as an optimum value,the welding effect is satisfactory when the median time is an optimum value.There is not droplet transfer when the median time is small and there is multitude droplets transfer when the median time is large.