Abstract: Weld geometry during underwater wet welding determines the mechanical properties of the resultant welded joints. Compared to those welded in an atmosphere environment, the factors that affect the weld geometry of the underwater wet weld are much more complicated. Underwater wet flux cored arc welding (FCAW) was conducted at different depths within a hyperbaric chamber. Mathematical models between underwater wet welding parameters and the weld width and reinforcement were established by response surface methodology (RSM). The effect of welding current,arc voltage,water depth and their interactions on the appearance of underwater wet weld was analyzed. The results show that the weld width increased with the increasing of underwater wet welding current and arc voltage,and the weld width decreased with the increasing of water depth. But as the water depth increased further,the effect of water depth on reducing weld width decreases. With increasing the welding current, the weld reinforcement increased and the effect of welding current on the reinforcement was stronger than arc voltage.