Forty-one samples of model compounds, 3,4’-disubstituted stilbenes (m-XSBY-p) were synthesized, and their molecular structures were characterized by 1H NMR and 13C NMR. The reduction potentials ERed of these model compounds were measured in anhydrous acetonitrile. For these measured ERed values, a quantitative correlation analysis was carried out by using the Hammett electronic effect constants and excited-state substituent constants of groups X and Y. A quantitative expression was obtained, in which the standard deviation is 0.063 V and is within the experimental error. The result indicates: the ERed of the model compounds were affected by both Hammett electronic effect constant and excited-state substituent constant of groups X and Y. Compared with the group Y, the effect of meta-group X on the ERed is important, and the electron-withdrawing effect of X makes a higher ERed and an easier reduction of model molecule. While the effect of para-group Y on the ERed is little and can be ignored.