Abstract: Environment pressure has negative effect on welding arc stability and droplet transfer in hyperbaric pulsed MIG welding. Through evaluating the MIG welding current waveforms, voltage waveforms, U-I diagrams and droplet transfer diagrams, the effects of pulse and base current on the welding arc stability and droplet transfer under different environment pressure were studied in detail. After a series of experiments, it was confirmed that the hyperbaric environment pressure can induce droplet transfer instability. The optimization of pulse peak current can improve the stability of the welding arc and droplet transfer effectively. By contrast, the optimization of pulse base current on arc stability has a positive effect, but the effect is relatively weak. This conclusion provides the effective theoretical and practical support for the stability of welding process in hyperbaric environment.