Abstract: The effect of hot-rolling deformation,solution and aging treatment on the microstructure and mechanical properties of Mg-12.20Y-2.45Zn-0.5Al(wt%)magnesium alloy containing LPSO phase was studied.The results show that the as-cast magnesium alloy containing LPSO after 500℃×25h solution treatment and 400℃×0.5h preheating treatment can be successfully rolled for two passes with large reduction.Rolling makes the 18R-LPSO phase at the crystal boundary broken and uniformly dispersed, and 14H phase in the crystal bent, while W phase decomposes, Al₂(Y, Zn)phase is broken and refined, which greatly improves the mechanical properties of the alloy. 200℃×24 h aging treatment after rolling further promotes the formation of a large number of small and dispersed 14H phases and stress release, and the mechanical properties of the alloy are significantly improved. The tensile strength and elongation reach 357.2 MPa and 6.8%, respectively, which are increased by 97.6%and 51.1%compared to those of the as-cast alloy, respectively.