The invention relates to a high-toughness carburized bearing steel with ultra-long contact fatigue life and a preparation method thereof, belonging to the technical field of alloy steel. The steel comprises the following chemical components in percentage by weight: 0.16-0.24% of C, at most 0.10% of Si, at most 0.10% of Mn, 0.30-1.50% of Cr, 1.5-4.5% of Ni, 0.30-1.50% of Mo, 0.02-0.10% of Nb, 0.3-0.9% of V, and the balance of Fe and inevitable impurities, wherein [N]+[O]+[H]+P+S<=0.0080%, and Ti<=0.0030%. The invention particularly relates to a high-toughness carburized bearing steel which has the advantages of high shock resistance load, stable dimension and ultra-long contact fatigue life in the serve process. Compared with the prior art, the invention has the advantages of high surface hardness, high core toughness, high dimensional stability, high bending fatigue strength limit and ultra-long contact fatigue life.