The capture power of wave energy converter is affected by the interaction between the buoy and wave. This study aims to investigate the interaction between the buoy and wave motion in low wave energy density seas using the hydrodynamic calculation software AQWA and to achieve a reasonable optimal configuration for the greater capture power based on the orthogonal experiment. Results show that the wavelength in the resonance state increases with the increasing of buoy mass and increases first and then decreases with the increasing of buoy diameter. Taking capture power as the optimization goal, applicability analysis denotes that the wave energy converter with the mass of 4.2 t and the buoy diameter of 4 m is suitable for the Bohai Sea and the north of the Yellow Sea. The maximum capture power of 150 W is obtained in the Bohai Strait owing to the wavelength of 14 m. This study provides a new idea for the mass control, diameter selection and arrangement of the wave energy converter.