Abstract: Digital twin technology has attracted the extensive attention owing to the unique advantages in intelligent manufacturing. In-depth research and widespread applications have been carried out on the conceptual models, theoretical frameworks, and practical deployment. The application of digital twins in metal additive manufacturing is receiving the increasing attention, serving as a bridge connecting the physical and digital worlds. By integrating the multi-physics simulation, internet of things perception, artificial intelligence, and big data analysis technologies, the virtual models precisely mapped to physical entities are constructed to achieve the real-time monitoring of the metal additive manufacturing production process, and to achieve the precise regulation and closed-loop optimization of the entire process, including materials, processes, and structures. The compatibility of digital twin technology with metal additive manufacturing was discussed in this article, the application scenarios of digital twin in metal additive manufacturing were investigated, and the challenges and development trends faced by digital twin and metal additive manufacturing were summarized.