Abstract: The microstructure, mechanical properties, and corrosion behavior of 2xxx, 5xxx, and 6xxx series Al alloys for substation terminal blocks were studied under simulated extreme corrosion conditions (high temperature/humidity). The corrosion resistance of three aluminum alloys was comparatively analyzed by means of weight loss method and corrosion morphology observation. The results show that among the tested alloys, 5xxx series exhibited the best combined performance in both hardness and conductivity. Under high-temperature and high-humidity corrosive conditions, the three aluminum alloys primarily exhibited pitting corrosion and intergranular corrosion. The inferior corrosion resistance of 2xxx series aluminum alloys was predominantly attributed to their high Cu content. Optimized Si content reduction was found to enhance the corrosion resistance of 6xxx series alloys. 5xxx series alloys exhibited superior corrosion resistance due to minimal intergranular precipitates. Microstructural characteristics, including phase morphology, precipitate distribution and elemental segregation, were determined to be the governing factors affecting aluminum alloys' corrosion behavior.