The establishment of digital twin model is at the core of the whole digital twin system. This paper analyzes the key technologies involved in the establishment of digital twin system, including complex system modeling, sensing and monitoring, Big data, dynamic data driving, and intelligent optimization and decision-making. On this basis, it is summarized that digital twin technology has the characteristics of transitioning from serial design to collaborative design, from post production validation to early validation, and from fixed models to dynamic models; And there are still problems in the application process of the digital twin system, such as the lack of unified standards, the establishment of modeling precision, the construction of real-time transmission channels, and the establishment and management of databases; Finally, prospects for its development were presented.