<p>This paper investigated the effects of trace rare-earth cerium on the inclusions and contact fatigue properties of high-carbon chromium bearing steel. An optimal rare earth addition range was proposed based on experimental findings, with thermodynamic explanations provided. By comparing GCr15 with different Ce contents (0.0005, 0.0076, and 0.0115&#xa0;pct) and GCr15 without Ce addition, the size distribution, types of inclusions and their effects on the contact fatigue life of GCr15 were systematically analyzed. Experimental results demonstrate that Ce addition effectively refines steel inclusions, with thermodynamic calculations revealing the transformation mechanism from Al₂O₃ to Ce–O–S and Ce–S compounds, consistent with experimental observations. While trace Ce addition (0.0005 pct) significantly enhances fatigue resistance, excessive Ce content (0.0115 pct) induces coarsening of inclusions. When the Ce content is 0.0076 pct, the improvement effect on the fatigue life of the bearing steel is the most significant. The rated life and median life reach 1.52×10⁷ and 4.46×10⁷ cycles respectively, which are 6 times and 4 times those of the steel without Ce addition. Further research revealed that both the fatigue life and the reciprocal of inclusion size follow the Weibull distribution. Based on this, a quantitative relationship between fatigue life and inclusion size under different rare-earth Ce conditions was established.</p>