In this report, the Cu2O/polyaniline(PANI)/stainless steel based electrode was prepared by electrochemical oxidation method. Cyclic voltammetry technique was carried out to research the electrochemical behavior of Cu2O/polyaniline nanotubes(PANI NTs). X-ray diffraction(XRD) and transmission electron microscope (TEM) were used for characterizing the as-obtained electrode. The reduction product of CO2 was analyzed by acetylacetone spectrophotometric method and gas chromatographic method. The results show that the Cu2O/PANI NTs are successfully loaded and exhibited excellent catalytic activity and CO2. The concentration of formaldehyde is 29.5μmol/L after reducing CO2 for 15h by photoelectrocatalysis with Cu2O/PANI/stainless steel based electrode.