Abstract: The metal transfer of dry hyperbaric GMAW was investigated with high speed camera system and infrared laser backlight. The experiments were carried out with three different wire-feeding speeds at ambient pressure of 0.1 MPa~2 MPa. The results show that the transfer mode changed finally to repelled transfer with the increase of ambient pressure. During droplet formation, the arc root always rose along the droplet surface to the welding wire, which caused asymmetric side force on the droplet. In addition, the electromagnetic force was resistance force due to contraction of arc root area in hyperbaric environment. Comparing the photos of arc root location at different ambient pressures, the arc root rising phenomenon also appeared at normal and low pressures. The generating condition and influential factors were derived by theoretical model.