In the state of long-term filling and storage of liquid missiles, the body and tank structure are often damaged by corrosion, which leads to fatigue cracks and even fractures. Fatigue life testing, scanning electron microscopy and energy spectrum analysis were used to study the fatigue crack initiation, propagation and fracture mechanism of 2195-T8 aluminum-lithium alloy pre-corroded in N₂O₄ for 180 days, and compared with uncorroded samples. The results show that the fatigue limits of the specimens tested in the two environments are 145Mpa and 118Mpa, and the cyclic stress reduction ratio is about 18.62%. During the pre-corrosion process, the sample forms an "occlusion zone" and forms a galvanic cell with the copper-rich phase particles at the same time, which further accelerates the corrosion process and forms the characteristics of multi-source crack initiation, and it is easier to crack from the non-metallic inclusion area. Affected by factors such as dislocation and accumulation between grains, it is found that it is perpendicular to the fatigue striations, passing through large grains, and passing through small-angle grain boundaries. The fracture morphology of the fatigue transient fracture zone in the two environments shows the characteristics of typical along-crystalline dimples and ductile fracture.