The relationship between the widths of supercooled liquid regions (△Tx) of Mg-based bulk metallic glasses (BMG) and bond parameters (i.e., electronegativity difference and atomic size parameters) was investigated. From the available experimental data in the literatures, it seems that for Mg-based BMG △Tx has a close correlation to bond parameters. It increases with the atomic size parameter (δ) and electronegativity difference (△x) of Mg-based alloys, which are defined by atomic radius and electronegativity. An equation was deduced for the first time by a linear regression analysis program in order to judge whether Mg-based multicomponent alloys can form metallic glasses.