In view of the characteristics of small wave height and short period in China sea area, a floating eccentric inner rotor wave energy generation device is proposed. Based on frequency-domain and time-domain analysis, the selection and optimization of the numerical calculation model of the eccentric inner rotor wave energy device are carried out, and the comparison with the experimental data of the pool is verified. The results show that the hydrodynamic performance and energy capture efficiency of the ellipse-circular wave energy device with the same length, width and draft depth are superior to those of the ellipse-circular wave energy device with the same length, width and draft depth. Increasing the mass of the inner rotor and the draft depth of the device can improve the hydrodynamic performance and energy capture efficiency of the device, and an optimal PTO damping coefficient can be found to make the energy capture power of the device reach the peak value. After selection optimization, the instantaneous output power surged from 1.16 kW to 2.29 kW, marking a 97.4% improvement, while the average output power ascended from 0.53 kW to 1.08 kW, reflecting a 103.8% increase.