This paper presents a pendulum-type wave energy conversion (WEC) system, which can change its natural frequency by a center of gravity adjustment mechanism. Based on this characteristic, a frequency and amplitude control (FAC) strategy is proposed to realize the maximum power point tracking (MPPT) of the WEC system. Firstly, the natural frequency of the WEC system is adjusted according to the peak frequency of the wave spectrum to make the device resonate with the waves, which is the frequency control (FC) method. The essence of the FC method is to change the position of the mass block inside the pendulum by controlling the angular displacement of the motor, so as to change the moment of inertia and recovery stiffness of the device. Secondly, the load of the mass block is very large, which brings a great challenge to the motor starting, so this paper proposes a soft-start control strategy to solve this problem. Thirdly, a weighted average method is proposed to calculate the intrinsic impedance of the WEC system under irregular waves, and then make the mechanical resistance of the power take-off (PTO) system equal to the intrinsic impedance of the WEC system by controlling the damping torque of the generator, which is the amplitude control (AC) method. By combining the FC method and AC method, the amplitude and phase conditions can be satisfied simultaneously to realize the MPPT of the WEC system. Finally, the feasibility and accuracy of the proposed control strategies are verified by simulation results.