Abstract: Determining the safe distance between prestressed crown anchor caverns and the powerhouse top arch is a prerequisite for constructing large underground powerhouses in gently inclined stratified rock masses using the "crown anchor caverns + penetrating prestressed anchor cables" excavation and support scheme.The design must ensure minimal disturbance to the surrounding rock of the powerhouse crown while maintaining economic efficiency and construction feasibility.To address this, we first employed an engineering analogy approach to analyze the safe distances of crown anchor caverns in numerous existing large underground powerhouses and their controlling factors.Subsequently, based on the theory of stable arch, the concept of plastic zones in surrounding rock, and excavation disturbance zones, a systematic method centers on the stable arch range of the powerhouse crown, with the plastic zone and excavation disturbance zone of the surrounding rock as validation criteria, was proposed to determine the safe distance.Finally, the Changyang Pumped Storage Power Station underground powerhouse was modeled and analyzed as a case study.The results indicate that the safe distance of the crown anchor caverns in this project should exceed 30 meters.The findings provide valuable guidance for optimizing excavation and support schemes in underground powerhouses with similar geological conditions.