If its floater is parallel to sea wave, the wave energy converter can sweep more wave energy at the same construction cost. To keep the floater parallel to wave, a self-modify design is proposed. The sea level difference of the floater will create a force to push the floater. And the force due to the rotation center will create a torque to force the wave energy converter aligned with waves. Increasing the sea level difference and the distance of the rotation center can increase the self-modify torque and the stability of the wave energy converter. After it keeps parallel to the wave, the floater will be able to collect more horizontal wave energy and extend the time which sea wave works on the wave energy converter.