Abstract: In order to improve the mechanical properties of magnesium alloys and explore new heat treatment processes,the effects of three aging treatments: single-stage aging, two-stage aging and reverse two-stage aging, on the microstructure and mechanical properties of extruded Mg-8.5Gd-3Y-0.5Zr alloy were studied by means of SEM analysis, hardness test and compression test. The results indicate that when the aging temperature is set to 225 ℃, the sample hardness is the highest, and the peak hardness value can reach 110.5 HV. In addition, compared with single-stage aging, the hardness and yield strength of the material have been improved after two-stage and reverse two-stage aging. Among them, the two-stage aged alloy achieves the highest compressive strength and hardness of 610 MPa and 117.9 HV, respectively. The results of this study provide a reference for the formulation of heat treatment processes of Mg-Gd alloys.