Abstract: The corrosion inhibition of an environment-friendly inhibitor (2-thiol-5-o-tolyl-1,3,4-thiadiazole) on 2024 aluminum alloy was studied by electrochemical method. The structure and orbital energy of the thiadiazole molecule was evaluated by quantum chemical semi-empirical method.The results show that the inhibitor can effectively decrease the rate of corrosion. The inhibition efficiency of the thiadiazole is up to 92% and the thiadiazole is a mixed type inhibitor. The inhibition mechanism is that the inhibitor reacts with aluminum alloy by adsorbing on the active centers.