In high-voltage transmission lines, insulators are essential for isolating electronic devices and supporting the line. Traditional detection methods face challenges when using unmanned aerial vehicles to capture insulator images due to blur-riness and the small size of insulators. This study enhances the Detr insulator defect detection model through a transfer learning strategy. A convolutional neu-ral network is trained on a limited dataset, providing it with prior knowledge. The Deformable Detr model leverages the insulator string dataset to enhance prior knowledge and accurately detect the bounding boxes of each insulator. A defect detection and classification device with multi-scale feature fusion is added to Deformable Detr. After classifier combination, images are categorized as undamaged , damaged, or flashover-damaged insulators. Corresponding loss functions are set, and after model training, parameters are optimized through backpropa-gation. Experimental results show a 97.5% accuracy on the test set, highlighting the network’s strong generalization ability.