Abstract: The wet underwater arc welding seam-tracking technology based on rotating arc sensor is introduced.An experimental system used to study the welding automation is established and welding parameters are found out at first for flux core arc welding based on experiments.The approach of calculating the welding current integration differences is adopted here to determine the weldinggun horizontal bias and vertical bias.Manifold digital signal process methods are performed on all sampled noisy signals to improve stability and reliability of results;Analysis on massive experimental data revealed that both horizontal bias and vertical bias can all be clarified clearly by this way;Further more, a manipulating system is carried out on above conclusions, and two kinds of different manipulators-Fuzzy controller and hybrid PID controller are designed separately to adjust the horizontal deviation and vertical deviation.The results of verifying tests approved the effectiveness of all above work.