The marine corrosive environment is complex, and the marine structure itself is also subjected to stress and other effects, which gradually highlights the corrosion and performance degradation problems of high-strength Al-alloy welded joints used in marine equipment. Herein, the corrosion behavior and performance degradation of welded joints of 7-series high-strength Al-alloy under different stresses, while immersion in Qingdao natural seawater at 5 ℃ for different times was studied via a lab simulation set, electrochemical measurement, universal test machine, SEM and XPS, in terms of the corrosion morphology, corrosion products, and degradation regularity of welded joints. The results show that as stress increases and immersion time prolongs, the corrosion tendency of high-strength Al-alloy welded joints increases, and their corrosion resistance gradually decreases; while the corrosion potential of the welded joint becomes more negative, the charge transfer resistance decreases, resulting in lower potential, higher corrosion sensitivity, and poorer corrosion resistance. When subjected to tensile stress exceeding 25%σ_s, as the pre stress increases, the proportion of oxygen in the corrosion products continues to increase, the corrosion product film is damaged, and the corrosion becomes more severe. With the increase of stress and immersion time, the elongation and cross-sectional shrinkage of the welded joint after fracture decrease, and thus the sensitivity to stress corrosion increases.