Abstract: Magnesium alloys are recognized as one of the most promising lightweight materials in the world. They are known as “green engineering metal in the 21st century”. Its application can solve the lightweight problem of key equipment and major projects and alleviate the increasingly severe environmental and energy crisis. However, the low strength of magnesium alloys, especially the poor performance in high temperature strength and creep deformation resistance, has seriously hindered its development. Therefore, alloying elements could also affect the deformation modes and the final texture either by dissolving in the Mg matrix or forming various precipitates. Among them, low-cost alkaline earth metal Sr is an alloying element which can improve the high temperature properties of magnesium alloys. Sr can improve the melting point of magnesium solid solution, diffuse slowly and has low density in magnesium alloys. It has been widely used in heat-resistant magnesium alloys. In recent years, researchers have been trying to optimize the Sr composition and its reasonable combination with other alloying elements, and have achieved fruitful results. The high temperature properties of heat-resistant magnesium alloys have been improved by adding Sr and/or other elements. At present, the more commonly used magnesium alloys are Mg-Al, Mg-Zn and Mg-RE. For Mg-Al system, adding alkaline earth element Sr can form a new phase at grain boundary besides fine grain strengthening. The phase has high melting point and thermal stability, which can prevent grain growth and grain boundary slip at high temperature and play the role of grain boundary strengthening, thus significantly improving the high temperature properties and creep resistance of magnesium alloys. For Mg-Zn system, the strength of as-cast Mg-Zn alloys increases to a certain extent by adding Sr element, but the plasticity is low. Therefore, researchers pay more and more attention to the effect of Sr on the properties of wrought magnesium alloys. In addition to fine grain strengthening, Mg-Zn-Sr ternary phase precipitates at grain boundary after adding appropriate amount of Sr in deformed Mg-Zn alloys. It has higher thermal stability and can pin grain boundaries, play the role of grain boundary strengthening, improve the high temperature mechanical properties of magnesium alloys, and improve the plasticity of wrought magnesium alloys. For the Mg-RE system, the proper addition of alkaline earth element Sr not only reduces the cost of the experiment, but also has a good refinement effect on the structure of the alloy. The content of the second phase increases and they are distributed more uniform at grain boundaries, which improve the high temperature mechanical properties of magnesium alloys. In this paper, the application and research progress of alkaline earth element Sr in Mg-Al, Mg-Zn and Mg-RE heat-resistant magnesium alloys are summarized. The strengthening mechanism of alkaline earth element Sr to improve the high temperature properties of magnesium alloys is discussed. The existing problems of Sr-containing heat-resistant magnesium alloys are pointed out, and the future development is prospected. It provides reference for improving high temperature performance of heat-resistant magnesium alloys.