Resonant wave power generation device by controlling the pendulum stiffness, cause resonance is consistent with wave frequency, which can extract energy efficiently through resonance with wave. The hydraulic system participates in the whole operation process, playing a crucial role in the reliable operation of power generation devices. According to the environment and working characteristics of the wave power generation, the reliable mathematical model of the power generation device is established. Meanwhile, the reliable predictions could be made by analyzing the reliable curve; the weak link of the system could be found through the qualitative and quantitative analysis of the fault tree model; and the optimal fault search order could be found according to the strategy of solving malfunction searching. Accordingly, theoretical basis and practical measures can be provided to achieve the goals of improving the reliability of the power generation device and making the device operate stably and reliably in the offshore.