Abstract: Based on the high-pressure water environment rotating arc welding system, the signal wave of welding current and voltage is obtained and statistically analyzed.A mass of short-circuit transten was found out.Through the groove scanning unit mathematical model, the inverter power model, the arc change model and the liquid bridge behavior model, the rotating arc sensing welding model under high pressure water environment was established.Combined with the actual welding experiment data under high pressure water environment, the influence of arc rotating frequency on the welding transition process was studied.The result shows when the groove is at a fixed degree, with the decreasing of rotating frequency from 20 Hz to 13 Hz, and then to 10 Hz, the phenomenon of open-circuit decreased gradually.The open circuit critical frequency was obtained under high-pressure water environment.