Under isothermal and linear heating conditions, the thermal stability of the three-dimensional metallic glass Ni68B21Si11, produced by rapid quenching of the denucleated melt (RODM), has been systematically studied using PE DSC7 differential scanning calorimetry in relation to denucleation of liquid alloy prior to rapid quenching, pre-anneal treatment of amorphous specimens, and cooling rate. The following results were observed. First, the thermal stability of metallic glass prepared by RODM is obviously enhanced because of the removal of pre-existing nuclei in advance. This is substantiated by the experimental data showing that the projected life of three-dimensional metallic glass Ni68B21Si11 is increased by an order of magnitude at 400 K. Secondly, pre-anneal treatment of the amorphous alloy leads to a reduction of temperature for the onset of crystallization, T-x, and crystallization heat, Delta H. Finally, quenching rates have little effect on the thermal stability of amorphous alloys.