Abstract: Retained austenite, as a key metastable phase in bearing steel, significantly influences its wear resistance. However, quantitative studies in this area remain scarce. Using GCr15 bearing steel as the research object, specimens with varying volume fractions and carbon contents of retained austenite were prepared by adjusting cryogenic treatment and tempering parameters. Dry sliding wear tests were conducted on both groups of specimens. The results indicate that when the carbon content of retained austenite is constant (1.0%, mass fraction), the wear resistance first decreases and then increases with increasing volume fraction of retained austenite. The initial decline in wear resistance is attributed to the gradual transformation of retained austenite during friction, leading to localized stress concentration and propagation of surface microcracks. As the volume JP2fraction increases from 7.3% to 13.8%, the wearJP resistance improves due to further formation of new martensite during friction. This phase transformation results in a significant increase in hardness, wherein hardness strengthening becomes the dominant mechanism. When the volume fraction of retained austenite is constant (5.0%), the stability of retained austenite enhances as its carbon mass fraction increases from 0.96% to 1.28%. More stable retained austenite better withstands impact during friction, thereby reducing wear spalling and improving the wear resistance of bearing steel. These findings provide theoretical support for designing heat treatment processes for highly wear-resistant bearing steel.