This present work focuses on investigating of efficiency of Acetaldehyde Ammonia Trimer (AAT) in the corrosion inhibition of 3003 aluminum alloy (3003AA) in carbonate medium in presence of chloride ions using electrochemical measurements, quantum chemical calculations based on DFT/B3LYP and Monte Carlo simulation methods for understanding the mechanism of corrosion inhibition. The results showed excellent inhibition corrosion of aluminum alloy with an efficiency reaching 92% for an optimum concentration of 10−3M at 298K. The adsorption results of the tested molecule obeyed Langmuir adsorption isotherm. The thermodynamic and kinetic parameters were determined and discussed. Furthermore, the capacity of AAT to act as an effective anti-corrosion agent was justified using these computational tools. Overall, the drawn-in-silico conclusions are in good agreement with experimental findings.