In the development and application of wave energy, how to improve the energy conversion efficiency has become one of the key issues in the large-scale utilization of wave energy. In this paper, the kinematic model of the oscillator is first obtained by separate force analysis of the wave energy device, then the kinematic model of the float relative to the ground is obtained by analysis of the whole, and then the kinematic model of the oscillator is solved according to the principle of relative motion. Finally, the optimal damping coefficients are solved for the two cases where the damping coefficient is constant and where the damping coefficient is proportional to the power of the absolute value of the relative velocities of the float and the oscillator.