Abstract: On the basis of MIG welding with constant wire feeding speed, the pulsed wire feeding MIG welding system was built up. The waveform of welding current and arc voltage were acquired through synchronous electrical signal acquisition system and the arc behavior and metal transfer processes were monitored by high-speed camera. The effect of pulsed wire feeding on MIG welding process was studied. It is found that the axial mechanical force on the droplet is the key factor on the form of the droplet transfer. In the same pulsed wire feeding frequency, the droplet transfer forms at the base value and the peak value of the pulsed wire feeding speed are different. And with the change of the pulsed wire feeding frequency, the droplet transfer modes are also different. Additionally, the weld width of pulsed wire feeding MIG welding is wider than that of constant speed wire feeding MIG welding, and the weld width increases with the increase of the pulsed wire feeding frequency.