Abstract: Magnesium and aluminum have strong chemical activity, easy oxidation, high thermal conductivity and a linear expansion coefficient. During welding of Mg/Al dissimilar metal, it will lead to formation of intermetallic compounds (IMCs) and defects such as pores and cracks, which has an important impact on microstructure and mechanical properties of welded joints. In this paper, welding technology of Mg/Al dissimilar metal in recent years is reviewed from solid phase welding, fusion welding and brazing. Welding mechanism and parameter optimization of each process and their modified technologies are discussed, and methods to control formation of Mg/Al intermetallic compounds and improve their microstructure distribution are summarized. At the same time, it puts forward prospect of Mg/Al dissimilar metal welding, and comment on the contents that should be focused on in the next step. It provides a certain theoretical basis and technical support for the subsequent research of Mg/Al dissimilar metal welding.