With the rapid development of high penetration of offshore wind power, it becomes a challenge to achieve effective and economical operation and maintenance (O&M) scheduling for offshore wind turbines. Moreover, uncertain factors such as climate change bring difficulties to decision-making for complex and frequent maintenance tasks. To overcome these challenges, this paper proposes a practical O&M path planning model for offshore wind farms in Zhanjiang, China. Multi-types of practical constraints and operation costs are taken into account to construct the O&M optimization problem. Furthermore, based on the practical O&M process, the proposed optimization problem can be divided into a master problem and a subproblem. A strengthened elitist genetic algorithm is introduced to solve the above bi-layer problem separately. Finally, multi-case study of the typical offshore wind farm in Guangdong, China verifies that the proposed O&M strategy can ensure lower economic costs and provide significant guidance for the operation of offshore wind farms.