A composite film consisting of ZnO and Chitosan (CS) is obtained on carbon steel via cathodic electrodeposition. Optimal CS concentration of electrodeposition of ZnO/CS film is determined by the method of polarization curves. It is shown that the ZnO/CS film obtained at the concentration of 0.6 g/L has the best corrosion resistance. The deposit is studied by scanning electron microscopy (SEM), Fourier transform infrared spectra (FT-IR) and X-ray diffraction (XRD). XRD results indicate that ZnO could be fabricated by electrodeposition in composite film. FT-IR results evidence the existence of CS in composite film. SEM results demonstrate that the quality of film is improved because of the addition of CS. The anticorrosion property can be attributed to that the existence of the CS macromolecules can improve the stability of the composite film. This kind of composite film has an anticorrosion application for metal corrosion protection.