Abstract: Through the full solution and aging at different temperatures, the microstructure and hardness of MgGd-Y-Zr alloy in the process of aging are studied. The results showed the segregation of the Gd and Y in the grain boundary can be eliminated almost completely by full solution treatment; aged at 200 ℃, the value of hardness increases rapidly at the beginning, and then emerges a little peak, after that the value rises slowly; the hardness begins to fall down slowly when reaches its peak hardness; The higher the aging temperature, the smaller the peak hardness, and the shorter the time of reaching the peak hardness.