Abstract: The effects of different solution and aging treatments on the microstructure and hardness of Mg-5Al-0.3Mn-1Gd alloy were studied by means of microstructure observation and hardness test.The results show that after solution at 430 ℃×2 h+565 ℃×4 h, β-Mg₁₇Al₁₂ phase in the as-cast Mg-5Al-0.3Mn-1Gd alloy is completely dissolved into the matrix, and the rare earth phase is dispersed in the matrix of Mg-5Al-0.3Mn-1Gd alloy in the shape of short rods, and the grain size of the alloy does not grow up significantly.After aging at 230 ℃for different time, with the increase of aging time, the number of second phase precipitated in Mg-5Al-0.3Mn-1Gd alloy gradually increases, and finally the fine second phase is concentrated in the local area, and the hardness of the alloy first increases and then decreases. The optimal solution and aging process for Mg-5Al-0.3Mn-1Gd alloy is 430 ℃×2 h+565 ℃×4 h solution+230 ℃×16 h aging.