Abstract: Mg₆₅Cu₂₀Zn₅Y₉Zr₁ bulk metallic glass matrix composite with a diameter of 2 mm was produced by copper mold casting. Upon cooling the Mg₆₅Cu₂₀Zn₅Y₉Zr₁ melt, Mg₂Cu acicular crystalline phase precipitates uniformly with a size of about 20 μm long and 1 μm thick while the remaining melt undergoes glass transition. Room temperature compression tests revealed that the high fracture strength up to 830 MPa and the plastic strain of 2.4% before failure are obtained for the Mg-based bulk metallic glass matrix composite. The formation of the Mg₂Cu phase was proposed to contribute to high strength and plastic deformation of the material.