Abstract: The pulsed MAG welding current and voltage waveforms in different air environmental pressures were analyzed using statistical method. The relationship between probability density distribution of arc voltage and current and the hyperbaric welding arc stability under different ambient pressure were also investigated in this paper. It is shown that the arc energy loss intensifies with increasing the environment pressure resulting in less stable welding process. A useful method to raise arc voltage setting to compensate the arc energy loss was used to obtain stable welding process. When arc voltage setting was increased 3 V and 5 V respectively in 0.3 MPa and 0.5 MPa hyperbaric environment, a stable welding process comparable with normal atmospheric welding has been realized. It is concluded that welding stability of hyperbaric pulsed MAG welding arc can be improved by higher arc voltage. This paper provided theoretical basis and experimental foundation for the hyperbaric pulse MAG welding to optimize and match the welding parameter.