Abstract: According to the vertical section of Fe-Cr-C ternary phase diagram with 1. 6% mass fraction of chromium and the high-temperature diffusion properties of carbon and chromium, the change process of carbon content distribution in the material during solidification and crystallization was analyzed, the formation mechanism of carbide inhomogeneity defects was explained, and the influence of carbide inhomogeneity defects on bearing contact fatigue life was discussed. The results show that the carbide inhomogeneity defects in GCr15 bearing steel included network carbide, band carbide and carbide-eliquation. The gap between liquidus and solidus of GCr15 steel was large, which caused obvious element segregation, and the carbide inhomogeneity defects were produced during solidification and crystallization.