The electrochemical reactions of carbon steel in LiBr solution have been investigated by electrochemical impedance spectroscopy. Inductive and capacitive loops were described in the Nyquist plots of electrochemical impedance at low and high frequency regions, respectively. On the basis of observation by confocal laser microscope, it was found that the localized corrosion site increased with the electrode potential, and that the dissolution rate of carbon steel increases with the increase of the localized corrosion. The electrochemical impedance spectra can be simulated with the empirical equation of the localized corrosion site and the electrode potential and equivalent circuit for the dissolution model of carbon steel.