Abstract: Relationship between metal transfer,arc shape and arc voltage was investigated with high speed camcorder system and digital oscillograph.Results show that metal transfer has a close relationship with arc voltage and the regular variation of arc shape.It shows that the regular changes of metal transfer make polarity spots spacing and arc beam resistance change and cause the arc voltage fluctuations,so that the arc shape changes regularly.Droplet transfer pattern changes and droplet size dereases with the increasing of welding current,different metal transfer mode has different arc voltage fluctuation,spraying transfer has lower variation of voltage but short transfer's arc voltage variation is bigger.