Abstract: Mg₆₀Cu_30-xY₁₀Si_x(x=0,1.0,1.8,2.5,5.0) bulk amorphous alloys were prepared by copper mould casting. The experimental results show that the alloy with x=1.0 has the largest glass-forming ability among Mg₆₀Cu_30-xY₁₀Si_x(x=0, 1.0, 1.8, 2.5, 5.0) alloys. The microhardness and fracture toughness of Mg₆₀Cu₂₉Y₁₀Si₁ alloy are also significantly improved compared with those of Mg₆₀Cu₃₀Y₁₀ alloy, but its supercooled liquid region (ΔT_x) decreases slightly. However, the reduced glass transition temperature (T_rg) of Mg₆₀Cu₂₉Y₁₀Si₁ alloy is larger than that of Mg₆₀Cu₂₉Y₁₀Si₁ alloy.