To address the challenges in identifying damage characteristics caused by multimodal Lamb wave propagation, dispersion effects, and signal attenuation in complex structures like steel bridge decks, this study proposes a deep learning-based damage detection method for U-Rib-Deck joints in steel bridge decks. By embed-ding squeeze-excitation (SE) attention mechanisms and long short-term memory (LSTM) networks into convolutional neural networks (CNN), combined with constructing datasets using Hilbert transform envelope curves, effective identification of typical fatigue damages in U-Rib-Deck joints is achieved. The research results demonstrate: ① Under damage conditions, the direct wave packet exhibits a rightward phase shift and amplitude attenuation, confirming the feasibility of using time-domain signal changes for damage detection. ② The SE-LSTMCNN model achieved validation accuracy and test accuracy of 93.67% and 95.00%, respectively, with the recognition accuracy for all types of damage exceeding 90%, indicating the model’s excellent applicability for damage detection tasks in steel bridge deck U-Rib-Deck joints. ③ The classification accuracy of the SE-CNN and LSTM-CNN models improved by 1.00% and 3.33%, respectively, compared to the baseline CNN model, while the SE-LSTM-CNN model further improved accuracy by 7.33% and 5.00% compared to the single-improvement models, validating the synergistic effectiveness of SE attention mechanism and LSTM for damage detection in steel bridge deck U-Rib-Deck joints; furthermore, using the envelope curve dataset increased the model’s validation accuracy by 21.33% compared to raw signals, demonstrating this method’s effectiveness in enhancing the SE-LSTM-CNN model’s ability to identify Lamb wave damage features. ④ The intelligent detection software developed based on MATLAB APP Designer achieved full-process optimization for damage detection, reducing errors from human intervention. This research is expected to provide a new technical solution for damage detection in steel bridge deck U-Rib-Deck joints.