Ocean wave energy is a renewable source that could reduce environmental impacts significantly than the traditional fossil energy. Many different ocean wave energy converters(OWECs), of various categories, have been proposed and prototyped, and power takeoff (PTO) system has been widely recognized as the most significant element for OWECs. Mechanical motion rectifier (MMR) has been used as a PTO system to harvest vibration energy for different applications and can achieve high energy conversion efficiency. This paper proposed a novel bottom-hinged flap-type energy converter with MMR to convert the bidirectional oscillation of the wave-surge flap to the unidirectional rotation of the generator. The working principle and dynamic modelling have been described in details, and the performance of MMR-based PTO has been verified by equivalent electric model. A small scale prototype has been tested in wave flume and the results show it can obtain 0.54W average power and 3.04W peak power with the excitation of 0.09m/2s.