Focuses on the application of digital twin technology in ultra-high voltage DC system, this paper analyzes the challenges and problems of digital twin technology in solving the scale, data, and application of ultra-high voltage DC systems, and systematically demonstrates the application scenarios and functional characteristics of digital twin technology in basic management, equipment management, safety management, and business operations. Based on business needs, a digital twin scenario and the innovative application technology system of digital power grid with digital twin technology as the key node are constructed. Based on the digital twin transformation of the power grid, its application scenarios are explored from the perspectives of data perception, model construction, and model application, improving the system′s perception and prediction capabilities in the virtual world. At the same time, it supports the intelligent application of the substations and the digital service demand of the new power system, provides specific and effective paths and references for the digital transformation of the power industry, and enhances the interactivity and security of the power grid, gradually achieves automation, intelligence, and unmanned operation of power grid business.