Magnesium rare-earth (Mg – RE) alloys exhibit the advantages of low densities, high specific strength and specific stiffness, desirable heat resistance, and good damping properties. The application of Mg–RE alloys in the aero-engine components can effectively reduce the equipment weight and system noise, improve the load capacity and maneuverability of aircraft. In this article, the classification of cast Mg–RE alloys is first introduced with different strengthening mechanisms. Various casting processes are reviewed and their effects on the microstructure and properties of Mg–RE alloys are also analyzed. Then the requirements for the use of Mg alloys in the existing aero-engine airworthiness standards and general standards are summarized, following by the application status of casting Mg–RE alloys in aero-engine and some other aerospace components at home and abroad. Finally, the problems and development trends of Mg–RE alloys used in aero-engine are discussed according to the actual engineering application requirements.