Abstract: A layer of WC coating was coated on the surface of GCr15 bearing steel by explosion spraying technique. The fatigue resistance of the bearing steel after explosion spraying was studied by fatigue tests and compared with that of bearing steel without explosion spraying. The results show that the fatigue resistance and fatigue life of GCr15 bearing steel decreased after explosion spraying. The fatigue cracks of the bearing steel without explosion spraying mainly originated from the surface machining tiny scratches, non-metallic inclusions and crystal slip belts. The fatigue cracks of the bearing steel after explosion spraying mainly originated from the cavity defects in the WC layer or non-metallic inclusions in the bearing steel near the interface.