Influence of 1wt% and 2wt% Li addition on the electrochemical corrosion behavior of pure Al was studied in 0.1MNaCl+0.01MH2SO4 acidic solution. Corrosion resistance was tested by free corrosion potential and electrochemical impedance spectrum (EIS). The composition and semiconducting properti of corrosion product films for pure Al, Al-1Li alloy and Al-2Li alloy formed at free corrosion potential were respectively analyzed by X-ray photoelectron spectroscopy (XPS) and Mott-Schottky (M-S) approach. The results showed that free corrosion potential of pure Al shifted in more active direction by Li addition, while its corrosion resistance was improved. Li, with high chemical activity, could participate in the film formation process and Li2O together with Al2O3 were existed in the product films. M-S plots revealed that Li addition did not change n-type semiconductor of corrosion product film on pure Al. But, the increasing of corrosion resistance was attributed to the decreasing of oxygen vacancy concentration in corrosion product films by Li addition to pure Al.