In the process of wave energy generation of the oscillation flapping-wing wave energy converter, the mechanical energy collected by the converter has the characteristics of fluctuation and randomness. In order to realize the energy is converted and stability of the electric energy is improved, an electric energy conversion system is designed to convert mechanical energy into stable and usable electric energy, which is then delivered to the charging unit for users.Taking the electric energy conversion system of the oscillating flapping-wing wave energy converter as the research object, the working principle of the system was analyzed,the structure and parameters were determined.The permanent magnet synchronous generator was used to convert the mechanical energy generated by the hydraulic motor into electrical energy, and the alternating current was converted into the stable direct current through rectifying and filtering, which was then charged into the charging unit after the DC/DC conversion. Based on the multi-energy domain bond graph modeling theory, the simulation model was established by using the software AMESim, and the proposed scheme was verified by simulation experiments.The research results show that the mechanical energy converted by the oscillating flapping-wing wave energy converter can be effectively converted by the system, and the electric energy can be rectified and stabilized, and the electric energy can be stored by the batteries.As a kind of electric energy conversion system of wave energy converter,it provided a theoretical basis for the research and development of the experimental platform of wave energy converter of oscillating flapping-wing wave energy converter.