The corrosion characteristics of various steels used by ocean wave energy equipment in sea water are investigated by electrochemical tests in this paper. The electrochemical experiments are carried out to research the corrosion rules of Q235, 20# steel, 16Mn and X42 through contrast experiments. Polarization curves and electrochemical impedance spectroscopy (EIS) are got by electrochemical workstation. Corrosion rates and corrosion potentials are analyzed from the polarization curves, and corrosion rules are founded. In addition, EIS is analyzed, and the analysis results are consistent with the results of polarization curves.