In order to improve the maintenance strategy of transformers in offshore wind power system, under the premise of ensuring reliable operation, an optimal selection method for the maintenance strategy of transformers in offshore wind power system is proposed, considering fault risks and uncertainties. Firstly, the fault risk cost model is analyzed in detail , based on which a life cycle cost (LCC) model for transformers in offshore wind power system is established. And the blind number theory is introduced to quantitatively calculate the uncertain parameters in LCC using mathematical models, thereby improving the accuracy of cost estimation. Then, from the perspective of cost management, the impact of maintenance plans on LCC is analyzed, and an optimization model for the maintenance strategy of transformers with the lowest LCC as the goal is established, which is solved by an improved Cuckoo algorithm. Finally, the example verifies that the proposed model and the optimal maintenance strategy method have strong operability, which can provide a certain reference value for the reliable operation of transformers in offshore wind power system.