We report here the electrochemical reaction mechanism of CO2 reduction catalyzed by aminopyridine cobalt complex. The thermodynamic energy barriers and the rate-determining step are unveiled on the basis of DFT calculation results. In addition, a computational investigation for the purpose of predicting the catalytic reactivity of a series of aminopyridine metal (Mn, Ni, Cr) complexes has also been carried out. The compound with Cr as central metal exhibits a low energy barrier in the rate-determining step. On the other hand, the electron-donating substituents are revealed to be able to reduce the energy barrier of the rate-determining step by increasing the eletrophilicity of the oxygen atom in C-OH moiety. Furthermore, the compounds with pi-pi conjugation in meso-positions cannot adsorb the CO2 molecule and therefore do not show catalytic activity for CO2 reduction. In contrast, the compounds with p-it conjugation in meso-positions exhibit a good catalytic activity for the reduction of CO2. (C) 2019 Elsevier Inc. All rights reserved.