Under stress corrosion conditions, local corrosion pits are generated on the surface of metallic materials, thereby inducing local stress concentration and accelerating the corrosion rate. However, the simulation and prediction of stress corrosion based on smooth specimens may lead to inconsistencies with actual service conditions. Therefore, conducting simulation research on stress corrosion under pre-corrosion conditions is of great significance for accurately predicting the corrosion evolution of materials. The differences in stress corrosion behavior of the aluminum alloy before and after pre-corrosion were analyzed. Potentiodynamic polarization curves of the aluminum alloy in 3.5% NaCl solution were measured using an electrochemical workstation. Simulation models for stress corrosion of the aluminum alloy before and after pre-corrosion were established, and the simulation results were compared with experimental data. The results indicate that, through steady-state and transient simulations, the electrode potential of the pre-corroded aluminum alloy shifts gradually negatively under applied stress, which is in good agreement with the experimental values. Moreover, the average and maximum anodic current densities as well as the corrosion depth of the pre-corroded aluminum alloy are higher than those of the uncorroded alloy. It is evident that the corrosion defects introduced on the aluminum alloy surface by pre-corrosion lead to active potential characteristics, thereby creating initial conditions for the occurrence of stress corrosion and significantly amplifying the promoting effect of stress on corrosion. Consequently, the stress corrosion behavior of the aluminum alloy becomes more severe after pre-corrosion. This study demonstrates that it is necessary to dynamically predict the corrosion process based on the evolution of surface corrosion morphology in stress corrosion simulation.