In order to reduce the curtailment of renewable energy, firstly the operating characteristics of the high proportion renewable energy power system is analyzed, and a flexibility demand model of the power system is proposed for units maintenance. Then, the differences in the adjustment ability of different units are analyzed, and the concept of unit flexibility is put forward. Considering comprehensively the adjustable capacity, minimum running time and outage time, operating cost and other indicators of the unit, the flexibility supply model of the unit is established. Based on the principle of equal flexibility of the power system at all times of the year, a unit maintenance model is established considering flexibility, and a unit maintenance strategy is formed based on the equal flexibility method. The results show that compared with the unit maintenance strategy of the currently widely used equal reserve method, the maintenance strategy of the equal flexibility method proposed can significantly reduce the annual renewable energy curtailment and increase the renewable energy consumption rate, which verifies the effectiveness of the model and method proposed.