The Mg-6Zn-6Al-0.5Mn-0.6Si-0.1Ca alloy has been produced in a steel crucible in an electric resistance furnace protectived by CO2+0.5%SF6. The microstructure of the as-cast alloy consisted of matrix–α(Mg) supersaturated solid solution, τ(Mg32(Al,Zn)49) ternary-phase and a small polygonal type Mg2Si phase in matrix. The τ(Mg32(Al,Zn)49) ternary-phase dispersion distribution in grain boundaries. After solution-treated, the amount of quasi-continuous net-shape ternary-phases reduce and small part of ternary-phases dissolve to the matrix which lead to the distribution on the matrix more uniform than as-casting condition in the alloy. The results of tensile, microhardness, impact toughness and corrosion property show that the alloy has better compressive properties.