5083 Al alloy sheets with different grain sizes (8.7-79.2 μm) were obtained by cold rolling and annealing. Their microstructures, intergranular corrosion (IGC), stress corrosion cracking (SCC), and crack propagation behaviors were investigated. The results showed that samples with coarse grains exhibit better IGC resistance with a corrosion depth of 15 μm. The slow strain rate test results revealed that fine-grainedsamples exhibit better SCC resistance with a susceptibility index(I_SSRT) of 11.2%. Furthermore, based on the crack propagation mechanism, grain refinement can improve the SCC resistance by increasing the number of grain boundaries to induce the corrosion crack propagation along a tortuous path. The grains with {011} orientation could hinder crack propagation by orientating it toward the low-angle grain boundary region. The crack in the fine-grained material slowly propagates due to the tortuous path, and low H⁺ and Cl^- concentrations.