Digital technology is leading the development and evolution of the fourth industrial revolution, promoting the gradual transformation of industrial economy into digital economy.In the era of digital economy, digital power grid is a new idea, new way and new insight for the construction and development of smart grid driven by technological evolution and demand upgrading. The definition, composition and characteristics of digital twin are expounded. The paper first proposes the digital power grid based on digital twin, analyzes the concept, characteristics of digital power grid and its derivative relationship with smart power grid, constructs the digital power grid architecture including physical power grid, perception layer, transmission layer, data layer, platform layer and application layer, and summarizes the key technologies of digital power grid.The digital power grid realizes the twin interaction between the physical world and the digital world, supports the digital operation of the power grid and constructs the digital energy ecology by constructing the power grid data closed-loop empower system.