Abstract: To verify the effect of laser on arc stability and metal transfer control in hyperbaric underwater MIG welding, the related experiment system was built in hyperbaric welding test chamber, and contrastive study on arc stability and metal transfer state with and without laser enhanced was conducted in different ambient pressure. The results show that the application of a certain power density of pulsed laser could offset the negative effect of underwater ambient pressure on metal transfer and welding processing stability, the size of droplet could be controlled by pulsed laser and the metal transfer frequency could be equal to the frequency of pulsed laser, the arc stability could also be improved, thus the welding processing stability could be improved.