It is always challenging to synchronously improve the strength, ductility and corrosion resistances, in the development of magnesium alloys. Herein, a concept called hierarchical precipitate embedded fine grain microstructure is proposed and implemented in an Mg-13Al (wt%) alloy by equal channel angular pressing and aging. Compared to the as-cast alloy, the modified alloy with the designed microstructure has high strength, good ductility, and improved corrosion resistance. The enhancement of mechanical properties is mainly attributed to the synergistic effect of fully recrystallized fine grains (~3.7 µm) and hierarchical β phase (Mg₁₇Al₁₂) precipitates. Although the formation of the hierarchical β phase precipitates in fine-grain Mg matrix can accelerate the initial corrosion in 3.5 wt% NaCl solution due to the galvanic corrosion, the ultimate corrosion resistance is successfully improved by the consumption of exposed Mg anodes and the synergistic barrier effect from the newly-formed corrosion products and corrosion-resistant β phases.