Abstract: Aiming at the technical problems that key components such as elastic hangers, droppers, and electrical connections in the catenary system of electrified railways are prone to defects such as loosening, strand scattering, and fracture, and existing detection methods are difficult to achieve comprehensive and accurate detection, this paper proposes a full-coverage scanning intelligent detection system for catenaries. The system can be mounted on catenary inspection vehicles, operation vehicles and other special rail vehicles, and completes efficient image acquisition of key catenary areas based on dual high-definition line-scan cameras; the improved YOLOv11n algorithm is adopted to achieve accurate positioning of target areas such as elastic hangers, droppers, and electrical connections, with a positioning accuracy of 96.52%, which is 2.14 percentage points higher than that of the original YOLOv11n algorithm; on this basis, the FastestDet lightweight model is used to complete defect identification of the three types of components, with an identification accuracy of 96.8%, which is 2.3 percentage points higher than that of the YOLO-Fastestv2 algorithm. The results of actual line tests show that the comprehensive defect identification accuracy of the system exceeds 90%, which can effectively realize pre-warning and accurate judgment of the status of key catenary components.