Abstract: The affected layer generated during the grinding process of hardened bearing steel has a direct impact on the performance of the parts, in order to improve the processing quality and efficiency of bearing parts, this paper conducted an experimental study on the formation law of affected layers in surface grinding hardened GCr15 bearing steel, the effects of grinding parameters on grinding force, grinding temperature, and affected layer thickness during the grinding process were studied, and the microstructure of the affected layer was observed. the variation law of microhardness of the affected layer was explored. Research has shown that the grinding force and grinding temperature increase with the increase of cutting depth, and the cooling method has a significant impact on the tangential grinding force; the heating rate during the grinding process is as high as 104 ℃/s, and the cooling rate is also up to 103 ℃/s; temperature is the main factor affecting the formation of the affected layer, and the thickness of the dark layer increases with increasing temperature, high temperature is a necessary condition for the formation of the white layer, after the grinding temperature exceeds the nominal phase transition temperature (745 ℃), the thickness of the white layer suddenly increases, and the ratio of the thickness of the dark layer to the white layer is greater than 4; the hardness of the white layer is higher than that of the substrate, and the surface hardness increases with increasing cutting depth, reaching a maximum hardness of 1057 HV, while the dark layer softens, with a minimum hardness of only 492 HV.