The oxidation behavior of NbC particle-reinforced cobalt-based wear-resistant alloy in the air from 950 to 1050℃ was investigated. The alloy belonged to the oxidation-resistant level at 950°C, the sub-oxidation-resistant level at 1000°C, and the non-oxidation-resistant level at 1050℃. The oxidation kinetic curves basically complied with the parabolic law. A mixed oxide layer consisting of CoCr2O4, CoNb2O6, Cr2O3, and Al2O3 was established on the alloy surface. The preferential in-situ oxidation behavior of the blocky NbC phase in the matrix resulted in the loose porous oxide layer and a non-uniform thickness. After oxidation of 1050℃/100h, a Cr depletion zone was formed in the matrix below the oxide layer, leading to the inability to re-form a continuous and protective oxide film after oxide peeling.