Recently offshore wind power is becoming a new growth trend of the renewable energy all over the world，but the imperfect pricing mechanism has seriously hindered its development.This paper first analyzes the domestic and international offshore wind power pricing mechanisms and the cost characteristics of offshore wind power，and then proposes a model to calculate the operation period costs.A real-world case with 28 offshore wind farms under construction in China is used in simulation.The results show that wind farms in sea areas with rich wind resources have lower costs，and the feed-in tariffs of wind power in different sea areas should be treated differently.The operation period costs are the most sensitive to the average annual full load utilization hours and initial static investment.