Linear sweep voltammetry (LSV), chronoamperometry (CA), electrochemical impedance spectroscopy (EIS) and surface observation were adopted to investigate electrochemical corrosion behavior of Ti-48Al-2Cr-2Nb alloy in NaNO3 solution (wt. 20%) with high potentials (7~16 V) and the influence of applied voltage on the corrosion behavior. Furthermore, Maxwell’s transmission line model was applied to fitting electrochemical impedance spectroscopy. The results showed that the current densities fluctuated greatly with the increase of the potential, and there was a transformation from non-uniform corrosion to uniform corrosion in the process of each sample. The number of adsorption reactions before and after corrosion decreased from 7 to 5. The decrease of the total corrosion resistance and the total time constant of the samples after corrosion experienced the process of the first increasing and then decreasing with the increase of the potential. The increase of surface roughness after corrosion decreased rapidly and then tended to be stable.