In terms of the weld tracking problem of marine welding robot, a Fractional Order Proportion Integration Differentiation (FOPID) control technology is proposed. According to the FOPID control principle, the FOPID controller is designed. In terms of the unique control parameters λ and μ of FOPID, the optimal theory domain range is determined by the step response test to optimize the FOPID controller. The various performances of FOPID controller are tested through the simulation tests and compared with the traditional Proportion Integration Differentiation (PID) controller. The results show that the FOPID controller possesses high accuracy, strong anti-interference and strong robustness, and can meet the work requirements.