Abstract: The rotating arc sensor is a kind of sensor used in welding automation,its application in the underwater welding is a new topic.The simulation computation of the electric arc model in the cases of the rotating arc sensor and high-pressure environment is carried out.The results indicate that when the air pressure is elevated from 0.1MPa to 1MPa,the the electric arc temperature elevates,and the temperature gradient nearby the welding wire simultaneously the electric arc temperature field transforms by the bell into the spindle-shaped.The comparision of the surface temperature on the weldment in the case of the two air pressures show that melting the same volume weld different needs more power when the air pressure is evevated.The comparision of the temperature of rotating center axis and welding wire axis at different air pressure verify the molton pool section is bowl-shaped,not finger-shaped when the rotating arc sensor is used.