Bulk armorphous Mg65Cu25Gd10 alloy of 12mm rods were prepared by water quenching the molten alloy in the stainless steel tube. Neither cavities nor voids are seen over the whole range and no contrast revealing a crystalline phase is seen over the transverse cross section. The glass transition temperature (Tg), crystallization temperature (Tx), the melting temperature (Tm) and the liquidus temperature (Tl) are measured to be 419K, 492K, 702K, 735K, respectively, for the Mg65Cu25Gd10 alloy with a diameter of 12mm. These temperatures are similar with those of the alloy with a diameter of 8mm produced by metallic mould casting. Both alloys have the same Vickers hardness about 260. Water quenching can further improve the critical diameter of glassy rods, so it is qualified for the formation of the bulk alloys.