Fretting wear occurring on the roller and raceway of rolling bearings is prone to reduce the reliability of bearings. In this study, fine particle bombardment (FPB) under different air pressures (0.3 and 0.6MPa) was performed on GCr15 bearing steel, and the microstructure and fretting wear properties of GCr15 bearing steel modified by FPB were systematically investigated. The results show that the surface structure of the samples undergone severe plastic deformation, which led to surface grain refinement and increased in dislocation density. Besides, the martensite bundle size decreased, and the density of LAGBs and HAGBs increased. Moreover, the FPB improved the microhardness and thickness of the deformed layer. The enhancement was positively correlated with the air pressure of FPB. Compared with the untreated sample, the wear volume of the FPB samples increased by 10.1% (0.3MPa) and 19.0% (0.6MPa), respectively. Therefore, the fretting wear resistance was significantly improved. The main wear mechanism changed from severe adhesive wear, abrasive wear, and fatigue wear to slight adhesive wear owing to the application of FPB.