Amorphous Zr₅₀Al_15−𝑥Ni₁₀Cu₂₅Y_𝑥 powders were fabricated by mechanical alloying at a low rotation speed from commercial pure element powders. The beneficial effect of Al partially substituted by Y in Zr₅₀Al₁₅Ni₁₀Cu₂₅ on glass-forming ability was investigated. The as-milled powders were characterized by X-ray diffraction and transmission electron microscopy. The results show that partial substitution of Al by Y can improve the glass-forming ability of Zr₅₀Al₁₅Ni₁₀Cu₂₅ alloy. Thermodynamic calculation of equivalent free energy shows that Zr₅₀Al_13.8Ni₁₀Cu₂₅Y_1.2 alloy has the highest glass-forming ability, which is in good agreement with the report of orthogonal experiments.