Abstract: Five kinds of Schiff bases with different structures were synthesized （N-phenyl benzoylimine, N-phenyl-2-hydroxyl benzoylimine and N-(2-hydroxyl) phenyl benzoylimine which possessed —OH, N-phenyl-4-nitryl benzoylimine and N-(4-nitryl) phenyl benzoylimine which possessed —NO2）. Cyclic voltammetry technique was used to investigate electrochemical redox behavior of these Schiff bases at glassy carbon electrode. Meanwhile, effect of pH on electrochemical redox reaction of Schiff bases was studied. The results demonstrated that these Schiff bases at glassy carbon electrode could be deoxidized and electrochemical reduction was an irreversible process; both different substituting groups (—OH and —NO2) in benzene and the same substituting group in different positions(benzene joined with carbon, benzene joined with nitrogen) had effects on electrochemical deoxidization of —CH＝＝N— group; in a buffer solution with varying pH, the concentration of H+ affected electrochemical deoxidization of —CH＝＝N— group; it was deduced that the mechanism for the electrochemical reduction process of —CH＝＝N— group was that firstly one electron was acquired in nitrogen, secondly one electron was acquired in carbon, and at last two protons were acquired.