Abstract: In response to the challenge of capacity mismatch in multi-energy complementary systems within complex terrain areas of the plateau, this paper focuses on the middle reaches of the Yarlung Zangbo River as the study area. It extends the Ward’s hierarchical clustering algorithm to the field of spatial layout optimization for wind and solar resource development and constructs a refined 8760-hour simulation framework for the four-dimensional coupling of hydroelectric-wind-photovoltaic-pumped storage. This approach breaks through the time resolution limitations of traditional monthly-scale planning. Furthermore, the study takes the under-construction Jiexu Hydropower Station and the planned Yongmu Pumped Storage Power Station within the basin as examples to investigate the layout and capacity optimization of hydroelectric-wind-photovoltaic-pumped storage systems. Based on the high-precision meteorological data set, the fine evaluation of the scenic resources in the study area indicates that the middle reaches of the Yarlung Zangbo River have a potential wind power development capacity of approximately 23.5 million kW and a solar energy development potential of about 238 million kW. The modelling results show the hydroelectric-wind-photovoltaic-pumped storage multi-energy complementary system based on the Jiexu-Yongmu power stations significantly regulates the utilization of new energy. On one hand, the complementarity between wind and solar energy enhances the utilization rate of new energy. On the other hand, the pumped-storage power station can mitigate the volatility of wind-solar output and increase the stability of power grid. Furthermore, if considering the flexibility of demand side, the installed capacity ratio of new energy to pumped-storage power stations would significantly increase.