Abstract: A self-powered system of the multi-joint bionic robotic fish using wave energy to generate power by joint swing is presented to solve the energy bottleneck problem for the long-term underwater service. The frequency characteristics and energy harvesting potential of wave are analyzed according to the random wave theory. An energy harvesting system generating power by joint swing is designed,and its electromechanical model is developed. Finally,simulation and single joint swing based power generation experiment indicate that this method is effective and applicable to designing self-powered system for long-term underwater service of bionic robotic fishes.