Additive Manufacturing (AM), commonly known as 3D printing, combines computer-aided design, material science and materials processing technologies. Based on digital model files, the special materials are stacked layer by layer through software and numerical control system to make parts. This new process provides new methods and ideas for the manufacturing industry. Although the basic principle of additive manufacturing is very simple, the microscopic mechanism is quite different from the traditional manufacturing processes, especially in the case of the rapid heating and cooling of metals during AM processing. More importantly, it is considered to be metastable state or even transient process, which is completely different from the steady-state processes considered in traditional casting processes. The purpose of this course is to provide students with a deeper understanding of metal additive manufacturing. After completing this course, they will have a certain understanding of the micro-mechanism in the process of AM solidification, and cultivate student’s ability of analysing problems from steady state to transients in macro to micro scales.