Ascorbic acid (AA) electrochemical sensor upon modification with porous g-C3N4(PCN)/Poly (3,4-ethylenedioxythiophene) (PEDOT) composite was constructed by a facile co-deposited method. The obtained PCN bearingmore oxygen-containing functional groups demonstrates excellent dispersion. Transmission electron microscopy (TEM) and Raman spectroscopy were performed to evaluate the structure and morphology of PCN/PEDOT composite. Detailed electrochemical behaviors of AA were investigated by cyclic voltammetry (CV). Under the optimal experimental conditions, the oxidation peak current was linear with the concentration of AA in a wide range from 10 mu M to 1500 mu M. The combination of PCN and PEDOT brings out large electro-active area and facilitates the electron-transfer greatly, which makes PCN/PEDOT composite appear to be an excellent choice as modified material for the construction of AA sensor. (C) 2018 The Electrochemical Society.