To be structural materials, the critical size is always a bottleneck of bulk metallic glasses (BMGs) due to the cooling rate restriction. Here, we report a developed alloy of Zr46Cu30.14Ag8.36Al8Be7.5, which can be cast into amorphous rods in 73 mm diameter by copper mould casting. The strong glass forming ability of this alloy is closely related to the Be addition, which not only suppresses the phase separation happening in the as-cast Be-free BMG but also sustains low Gibbs free energy difference for crystallization. This finding will stimulate more interests in developing BMGs and their industrial applications.