Abstract: Transition metal oxide is a kind of catalyst with high catalytic activity for electrocatalytic oxygen evolution reaction. However, the catalytic activity is limited by the low electronic conductivity. The effective way to construct high performance electrode material or electrochemical catalyst is combining the nano material with conductive matrix material. The polymerized porphyrins supported on C₃N₄ were prepared by solvothermal method. The Co₃O₄/NC catalyst was prepared by Co modification and heat treatment of BDA-PY/C₃N₄. The physicochemical properties of the catalyst were characterized by XRD, SEM, TEM, XPS and FT-IR, and so on. The results indicate that Co₃O₄/NC-600 possesses a super-small nano-Co₃O₄ structure and high nitrogen content. The strong chemical bond between pyridinic N of the nitrogen-doped carbon and Co is formed, resulting in a synergistic effect, which makes the catalyst show good catalytic performance in OER reaction. Its Tafel slope is only 66.4 mV/dec and the minimum overpotential is 343.3 mV when the current density reaches 10 mA/cm².