The Y56Al24Ni20 and Y36Ce20Al24Ni20 alloy can be fabricated into bulk glassy form of 3 and 5mm in diameter respectively by copper mold casting methods. The formation and thermal stability of yttrium-based amorphous alloys are investigated by means of X-ray diffraction and differential scanning calorimetry. Bulk Y36Ce20Al24Ni20 amorphous alloys exhibit a distinct glass transition temperature，a wide supercooled liquid region ΔTx and a high reduced glass transition temperature Trg of which are 63K and 0.70 K, respectively. The results show that the addition of Ce in Y56Al24Ni20 alloy may improve the glass forming ability and the thermal stability.