In view of the problems such as complex procedures, high construction difficulties, and high safety risks during the expansion excavation process of inclined shafts in the water diversion tunnels of pumped storage power stations, taking a pumped storage power station in Xiamen City as an example, this paper discusses the key technologies for the expansion excavation of long inclined shafts, including optimizing the construction procedures and methods for the expansion excavation of long inclined shafts, reasonably arranging the construction platforms and lifting systems for the expansion excavation, and formulating effective preventive and treatment measures for shaft blockage during the expansion excavation. Through the comprehensive application of these key technologies, the maximum monthly progress of the expansion excavation in this project reached 96 m, achieving the safe and rapid construction of the expansion excavation of the long inclined shaft in the water diversion tunnel.