Aiming at the pitch phenomenon with inverted pendulum motion characteristics produced by the fixed offshore wind turbine under the combined action of random wind load and wave load, an Active Rotary Inertia Driver (ARID) control system is proposed to control the pitch of the offshore wind turbine. The ARID control system uses a servo motor to drive the rotating inertia mass to generate a torque opposite to the structural swing direction, thereby reducing the pitch motion of the wind turbine. Based on Lagrange principle, the theoretical analysis model of the offshore wind turbine-ARID control system is established. The effectiveness of the offshore wind turbine-ARID control system is verified by Simulink, and the influence of the system parameters (the control algorithm parameters, rotary inertia ratio, etc.) on the control effect is analyzed. The shaking table test of the offshore wind turbine-ARID control system is designed, and a variety of load excitation forms are set to verify the stability and broad-spectrum effectiveness of the control system. The numerical simulation and test results verify the correctness of the analysis model, and show that the ARID control system is of a significant control effect on the swing control of the offshore wind turbine, which lays a theoretical foundation for the swing control of ARID control system on the structure with inverted pendulum motion characteristics.