Digital twin is a computer informational transformation technology of “combination of virtual and real”, it is accelerating the implementation in various fields. Based on the digital twin technology, relying on 3D design model of nuclear power plant. To use the method of modular design, this paper combed the relationship between the three-dimensional model and construction progress, established the corresponding relationship of model granularity at different levels, and used VR/AR technology for simulation to construct the 4D nuclear power plant model realizing the collaborative design and construction of nuclear power project. This paper has studied and adopted artificial intelligence algorithm and developed the software of intelligent layout of nuclear island pipelines in nuclear power plant, which has realized the intelligent layout design of nuclear power to a certain degree. On the basis of the above research and application, aiming at the cost of the design and construction of nuclear power plant, this paper expands the 3D and 4D models of nuclear power project to 5D model, and further studies the 6D model of nuclear power project based on the technology of digital twin, so as to meet the needs of operation and maintenance, simulation test and asset management after the completion and handover of nuclear power plant. Because of the development of chip, sensor, internet of things, software algorithm, machine learning and other technologies, digital twin will have more imagination space for application.