In this study, we addressed the problem of maximum output power in wave energy devices by analyzing the forces acting on the buoy and oscillators under the influence of ocean waves. The motion models for both floating devices and oscillators were developed, and algorithms were devised to determine the maximum output power of wave energy devices. When the buoy was only undergoing linear motion, a second-order ordinary differential equation could be established with displacement as the unknown variable. The main objective of this study was to maximize power, which was composed of the power generated by the damper, with the damping coefficient as the decision variable. Additionally, it was necessary to consider the following constraints in the motion equations: gravity, buoyancy, wave excitation force, added inertia force, wave damping force, static water restoring force, and the reactive forces from the damper and spring. By solving an unconstrained minimization problem related to the damping coefficient, the solution to achieve maximum power during linear motion could be found. When the rotation of the buoy was considered, we needed to modify the objective function to include the contribution of the rotational damper and introduce the rotational damping coefficient as a decision variable. Furthermore, we needed to add torque analysis as a constraint to account for the rotational motion of the buoy. Ultimately, the wave electric power generation system would provide the optimal power design solution that took into account both linear and rotational motions of the buoy.