Ocean energy, as a kind of renewable resource, plays an important role in China’s low-carbon development and meeting its goal of “carbon peaking and carbon neutrality”. The paper aims to calculate the cost of ocean power generation in China and make a medium and long-term forecast. Meanwhile, the offshore wind power development experience and the Levelized Cost of Energy (LCOE) cost pricing model is used for analysis and verification. The results shows that it features a high cost without economical efficiency in the initial stage; With the continuous expansion of installed capacity, the cost will be significantly lowered but the economical efficiency is moderate; the cost will fall significantly when the installed capacity reaches to a 100 MW level, and it has strong economical efficiency. The government should provide policy and financial support for ocean power generation industry; enterprises need to strengthen technological innovation and complete the industrial chain to improve the economical efficiency of scale utilization.