Because of the characteristics of low density and good recycle, magnesium alloys are praised of the green engineering material, which have a widely applied prospect in the fields of automobile, motorcycle, aerospace and other industries. But the welding problem has become a key constraint on their application. Laser welding will be an important joining technique for magnesium alloys with their increasing applications. Compared with other fusion welding techniques, laser welding is one of the ideal methods for magnesium alloy because of its characteristics such as deep penetration of welds and excellent performance of joints. To date, two types of industrial lasers, i.e., CO2 and Nd:YAG lasers, have been used to investigate the weldability of magnesium alloys. In this paper, the process methods, welding materials, joint properties (mainly for mechanical properties and corrosion resistance) and metallurgical defects (mainly including porosity and cracking) of laser welding of magnesium alloys are analyzed. The research status of laser welding of magnesium alloys at home and abroad is summarized. The development trends of research and application of laser welding of magnesium alloy are reviewed.