Both Backward Bent Duct Buoy (BBDB) and Japanese “Mighty Whale” are offshore floating Oscillating Water Column (OWC) type wave power devices. The investment of “Mighty Whale” is comparatively huge and its wave-to-wire efficiency is about 5.3%. Based on the reports of model experiments and over-3-year sea trials of “Mighty Whale”, recent progress of air turbines and the studies of BBDB and air turbine in Guangzhou Institute of Energy Conversion (GIEC), Chinese Academy of Sciences (CAS), the cost-performance ratio of wave power boat based on the BBDB principle is evaluated. According to the RMB purchasing power in 2014, if the incident wave power density is 16 kW/m, the boat lifespan is 15 years, and the air turbine efficiency is high enough to make the wave-to-wire conversion efficiency reach 30%, the cost of electricity generated by this boat can drop to below 1 CNY/kWh. If the incident wave density or the wave-to-wire efficiency is higher, this cost will decrease further. And, the mobility of the self-propelled wave power boat solves the underwater residue problem caused by the complex mooring of traditional wave energy converter; also, it helps the wave power boat in moving to a port to avoid typhoons and adjusting to the wave direction. Therefore, the BBDB wave power boat technology has broad prospects for developments.