Abstract: The synergistic inhibition effect of lithium molydbate and benzotriazole for carbon steel in lithium bromide solution was evaluated by means of weight loss methods during immension. The combination of 0.02 mol/L lithium molydbate and 0.02 mol/L benzotriazole shows the best result. In terms of (polarization) curves, SEM and AES, the probable mechanism involved was that the passive film, which was composed of lithium molydbate, molydbate oxide, iron-benzotriazole and ferric oxide, was formed on the surface of carbon steel to retard the cathodic reaction.