Abstract: Disclosed is a quasicrystalline phase-reinforced Mg-based metallic alloy with high warm and hot formability, and making method thereof. The metallic alloy comprises a composition of Mg—1˜10 at % Zn—0.1˜3 at % Y, in which a two-phase region consisting of a quascrystalline phase and a magnesium-based solid solution phase exists. Constituting a matrix structure, the Mg-based solid solution phase (&agr;—Mg) is formed as a primary solid phase upon solidification. The quasicrystalline phase serves as a second phase and forms, together with the Mg-based solid solution phase, a eutectic phase, thereby reinforcing the matrix. The materials obtained through the hot rolling or extrusion of the cast alloy have an increased volume % of the second phase and thus show significantly increased strength.