Preventive maintenance of wind turbine can effectively improve the reliability of wind turbine. This paper firstly sets single component reliability of wind turbine as constraint condition, single component minimum unit time maintenance cost as objective function to obtain optimal maintenance cycle and maintenance times. On this basis, the components which meet certain conditions are repaired, then the opportunistic maintenance model of wind turbine is built. Lastly, it takes the minimum total cost under opportunistic maintenance as objective function and the wind turbine availability as constraint condition, and then solves this model to obtain optimal threshold of opportunistic maintenance and minimum total maintenance cost using genetic algorithm. The example analysis shows that the model can effectively save the total maintenance cost. This study has some reference significance for the maintenance department to make the maintenance plan. This work is supported by Science and Technology Project of State Grid Corporation of China (No. 522727160002).