This review summarizes the current progress in research on heat-resistant magnesium (Mg) alloys. Mg alloys are widely used in aerospace, automotive, and electronic industries due to their low density, high specific strength, and excellent damping properties. However, their mechanical properties degrade at high temperatures, especially for common commercial alloys like AZ91D. To improve heat resistance, researchers have focused on inhibiting thermally unstable phases or promoting thermally stable precipitates through solid solution or precipitation strengthening. The review discusses various Mg alloy systems, including Mg–Al, Mg–Zn, and Mg–rare earth (RE), and compares their mechanical properties and strengthening mechanisms. Mg–RE-based alloys, such as WE, EZ, EK, and QE, show better heat resistance and maintain high mechanical properties at temperatures up to 300°C. The review also highlights deformation mechanisms at high temperatures, including dislocation slips, twinning, and grain boundary sliding. At high temperatures, basal slips are less effective, and twinning becomes more important for plastic deformation. Twinning, although not the dominant mechanism, plays a crucial role in coordinating deformation in Mg alloys. Grain boundary sliding is another essential deformation mode under high-temperature and low-stress conditions. The review emphasizes the importance of understanding these mechanisms to develop more heat-resistant Mg alloys and expand their applications in high-temperature environments. Keywords: magnesium alloys; mechanical properties; heat resistance; microstructures; high temperatures; strengthening mechanisms.This review summarizes the current progress in research on heat-resistant magnesium (Mg) alloys. Mg alloys are widely used in aerospace, automotive, and electronic industries due to their low density, high specific strength, and excellent damping properties. However, their mechanical properties degrade at high temperatures, especially for common commercial alloys like AZ91D. To improve heat resistance, researchers have focused on inhibiting thermally unstable phases or promoting thermally stable precipitates through solid solution or precipitation strengthening. The review discusses various Mg alloy systems, including Mg–Al, Mg–Zn, and Mg–rare earth (RE), and compares their mechanical properties and strengthening mechanisms. Mg–RE-based alloys, such as WE, EZ, EK, and QE, show better heat resistance and maintain high mechanical properties at temperatures up to 300°C. The review also highlights deformation mechanisms at high temperatures, including dislocation slips, twinning, and grain boundary sliding. At high temperatures, basal slips are less effective, and twinning becomes more important for plastic deformation. Twinning, although not the dominant mechanism, plays a crucial role in coordinating deformation in Mg alloys. Grain boundary sliding is another essential deformation mode under high-temperature and low-stress conditions. The review emphasizes the importance of understanding these mechanisms to develop more heat-resistant Mg alloys and expand their applications in high-temperature environments. Keywords: magnesium alloys; mechanical properties; heat resistance; microstructures; high temperatures; strengthening mechanisms.