The intergranular corrosion behavior of 2050 Al−Li alloy subjected to non-isothermal aging (NIA) treatment with varying pre-deformation amounts was investigated. Results indicate that the resistance to intergranular corrosion improves with increasing pre-deformation amouts. However, when the pre-deformation amount reaches 20%, the corrosion resistance deteriorates. Microstructural analyses via transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) reveal that as pre-deformation amount increases, the fraction of high-angle grain boundaries (HAGBs) decreases, while the proportion of low-angle grain boundaries (LAGBs) increases. This change provides additional nucleation sites for precipitates, leading to a reduction in T₁ phase size and an increase in T₁ phase density. The finer T₁ phases contribute to a lower localized potential difference within the grains, slowering corrosion propagation. Furthermore, during corrosion, preferential dissolution of Li results in Cu enrichment along grain boundaries, which further reduces the intergranular corrosion resistance.