The work aims to improve the dispersibility of carbon nanotubes (CNTs) and the anti-corrosion capability of A4 steel coatings. CNTs were modified by the chemical and physical treatment. The corresponding performance of modified CNTs was characterized by FTIR, TEM and TGA. Then the modified CNTs were added in the ceramic coating to prepare the CNTs-reinforced phosphate ceramic coatings (CRPCC) with the varying amounts of modified CNTs. The corrosion resistance of CRPCC was investigated by electrochemical test. The modified multiwalled CNTs were distributed more uniformly and the agglomeration was more obvious. The surface of modified CNTs was covered with active agent successfully and the oxy-gen-containing groups in the sidewall accounted for about 20wt.%. From the electrochemical results, the content of Cl, O elements at the junction between the substrate and coating could be effectively reduced by the CNTs and topography of CRPCC substrate after corrosion was good. At the later corrosion, the impedance modulus reached 106 kΩ?cm2 and PE was up to 94%. The dispersibility of CNTs can be improved by the mixed modification. The addition of CNTs can improve the corrosion resistance of coatings.