This paper aims to explore the application of isolation technology in high voltage design of energy storage systems (ESS), with a focus on analyzing the characteristics of optical isolation, magnetic isolation, and capacitive isolation technologies and their performance in different application scenarios. By combining technical comparison, application analysis, and case studies, this paper elaborates in detail on the application of isolation technology in improving system safety, reducing electromagnetic interference, achieving signal and energy transmission, and facilitating measurement and control in high voltage environments. The results indicate that reasonable selection of isolation technologies can effectively improve the safety and reliability of high voltage energy storage systems, providing theoretical basis and practical guidance for the design and optimization of high voltage energy storage systems.