In this study, the electrochemical behavior of zinc meso-substituted porphyrins in the presence of imidazole is examined by using both cyclic voltammetry (CV) and density functional theory (DFT) methods. The results show that the first half-wave oxidation potentials (1st E-1/2) of zinc porphyrins complexed with imidazole all move to the negative side, while the second ones (2nd E-1/2) move to the positive side, resulting in larger half-wave oxidation potential splittings of the two oxidation states (Delta E = second E-1/2 first E-1/2) comparing with the zinc porphyrins. By employing DFT calculations, we have found that both sterically controlled inter pi-conjugation between porphyrin rings and meso-substituted phenyl groups and deformation of porphyrin rings do play important roles in contributing to the half-wave oxidation potentials. Imidazole exhibits strong effects on the deformation of porphyrin rings which is dominant in determining the first E-1/2 while the inter pi-conjugation between porphyrin rings and meso-substituted phenyl groups mainly contributes to the second E-1/2 . Without imidazole, the inter re-conjugation between porphyrin rings and mesa substituted phenyl groups is the only important criterion which effects both first E-1/2 and second E-1/2 of zinc porphyrins.