The invention belongs to the technical field of materials, and relates to an ultra-high-strength heat-resistant gear bearing steel with ultra-hardened surface layer and a preparation method thereof. The chemical composition of the steel comprises the following chemical components of, in percentage by mass, 0.08-0.18% of C, 10.0-16.0% of Co, 3.0-8.0% of Ni, 3.0-7.0% of Cr, 3.0-6.0% of Mo, 0.5-2.0%of W, 0.2-1.0% of V, 0-0.1% of Nb, and the balance Fe and impurity elements. According to the method, vacuum induction melting, vacuum induction melting and vacuum arc remelting or vacuum induction melting and electroslag remelting are adopted for smelting. Steel ingots are diffusion annealed and forged into steel products. Steel samples are subjected to preliminary heat treatment, carburization and final heat treatment, the tensile strength of the steel is not less than 1900 MP a, the yield strength is not less than 1600 MP a, and the carburized surface hardness is not less than 850 HV (equivalent to 66 HRC). The method has the advantages that compared with the prior art, the method has higher tensile strength, yield strength and relatively good plasticity, toughness and heat resistance,has excellent surface carburization super-hardening performance and fatigue performance, and achieves good matching of the core super-toughening and surface super-hardening.