Abstract: Standard deviation(SD) and the reciprocal of coefficient of variation(CV) of welding voltage are used as the index of arc stability.The arc stability of underwater wet flux-cored arc welding in different welding conditions was studied based on underwater wet welding experiments.Sensitivity models of arc stability have been built and sensitivities of welding parameters on arc stability, such as welding current, voltage, speed and water depth, were analyzed.The results showed that the arc stability got worse as water depth increased.Especially in shallow water, the arc stability decreased dramatically as the water depth increased.Arc stability also decreases with the increasing of welding speed.The welding voltage has a great influence on arc stability and increasing the welding voltage appropriately will improve the arc stability.