Abstract: The rotational bending fatigue performance of SUJ2S1 high carbon chromium bearing steel was tested using a simply supported beam rotational bending fatigue testing machine, and the fatigue limit rise and fall diagram, fatigue strength-fatigue life curve, and survival rale-fatigue strength-fatigue life curve of the material were plotted. Using field emission electron microscopy to analyze the causes of fatigue fracture in materials. The results show that the fatigue limit of high carbon chromium bearing steel was 458 MPa, and the fatigue limit at a survival rate of 90% was 300 MPa. There were mechanical processing defects and Al₂O₃ inclusions on the surface of the test steel, which ultimately led to fatigue fracture of the material.