Abstract: In order to determine the cause of fracture failure in bolts used for railway turnouts, this study conducted inspections, evaluations, and analyses on the fractured bolts using methods such as visual inspection, physicochemical testing (chemical analysis, hardness testing, metallographic examination), and fracture surface analysis. The results showed that the failure mode of the bolts was high-cycle fatigue fracture caused by bidirectional bending. The root cause of the fracture was the presence of a decarburized layer at the thread region, which significantly reduced the material's fatigue resistance. By analyzing the failure mechanism of the bolt fracture, the study provides practical guidance for the manufacturing processes and quality control of turnout bolts, thereby enhancing their durability and reliability while reducing the risk of fracture.