2A12 aluminum alloy used for a suspension structure of an aircraft adopts a dynamic corrosion-fatigue coupling test after pre-corrosion, and the fracture behavior soon occurs. It was necessary to find the failure reason and propose solutions. Using the self-made horizontal dynamic corrosion-fatigue test device, carry out the corrosion fatigue test after the 2A12 aluminum alloy pre-corrosion until the sample breaks. At the same time, 2A12 aluminum alloy corrosion and fatigue alternate test were carried out to analyze the fracture corrosion morphology, element content, and valence changes. Corrosion fatigue mechanism of 2A12 aluminum alloy was obtained under two test conditions. 2A12 aluminum alloy was composed of an aluminum matrix and a variety of dispersed alloy strengthening phases. When there was a pre-crack, the 2A12 aluminum alloy would quickly undergo fatigue fracture under the alternate action of corrosion fatigue, and the crack almost penetrated the entire section, and there were many corrosion products near the crack, aluminum oxide. After 2A12 aluminum alloy was pre-corroded, a corrosion cell was formed between the substrate and the oxide film on its surface. The initial pitting corrosion pitted and produced a large number of corrosion products. The bottom of the corrosion pit became the source of cracks due to stress concentration. Under the synergistic effect of corrosion fatigue, cracks were gradually initiated and expanded radially, fatigue fracture behavior occurred quickly, and there was no corrosion product at the crack propagation zone. Therefore, when 2A12 aluminum alloy was used as an aircraft suspension structure, the surface must be treated with anti-corrosion to avoid the formation of corrosion pits, and then slow down corrosion fatigue fracture process.