Effects of heat treatment on the mechanical properties in squeeze cast Mg-10wt%Li-3wt%Al and Mg-10wt%Li-5wt% Al alloys have been ivestigated. The as-cast microstructure consists of a mixture of α, βand AlLi. The best combination of hardness and tensile strength were obtained after solution treatment at 350℃ for 1 hour for Mg-10wt%Li-3wt%Al and 370℃ for 1 hour for Mg-10wt%Li-5wt%Al, respectively. Various microstructural features such as the ratio of α/βvolume fraction, the orientation relationship between α and β grains and shape change of α phase were observed after heat treatment. Strengthening of the Mg-Li-Al alloys is due to the precipitation of AlLi in the β phase matrix, dissolving of Al into the matrix during heat treatment and reprecipitation of α platelets during cooling after heat treatment.