Abstract: The dry-wet alternation and constant stress conditions of aluminum alloy thin-walled structure of underwater training suit were simulated under laboratory conditions. The failure mode and failure mechanism of the thin-walled structure were proved by observing the surface corrosion morphology of aluminum alloy samples, testing the tensile properties and analyzing the fracture surface. The results show that the aluminum alloy thin-walled structure of the underwater training suit was prone to pitting corrosion during use. Pitting corrosion was the main reason for the decrease of the tensile strength of the matrix material. Under the action of stress (pressure, assembly, etc.) under various working conditions, microcracks were initiated at the pitting pits, resulting in microleakage problems of the structure during actual use.