The work aims to improve microhardness and corrosion resistance of Ni-Co-CeO2 nanocomposite coatings. The Ni-Co-CeO2 nanocomposite coatings were prepared in the method of electrodeposition under ultrasound condition. Codeposition technology experiment involving Ni2+, Co2+ and nano particles was studied in the method of orthogonal experiment. With micro Vickers hardness as examining index, optimum technological conditions of electrodeposition were determined based upon range analysis, and corrosion resistance of the Ni-Co-CeO2 nanocomposite coatings in 3.5wt% NaCl solution was studied based upon po-tentiodynamic polarization. The surface morphology, microstructure and elementary composition of the nano composite coatings were studied by SEM, XRD and EDAX. Under the effect of ultrasound cavitation, nano rare earth CeO2 was dispersed in the coat-ings, the nanocomposite coatings were refined. As a result, microhardness of the coatings increased from 264.34HV to 486.82HV, corrosion resistance was improved, and Jcorr value decreased to 2.012 μA/cm2 from 6.305 μA/cm2. Provided with the experimental condition of 160 W ultrasonic power, the optimum technological conditions of coatings preparation are, plating bath temperature of 55 ℃, current density of 2 A/dm2, CeO2 concentration of 1 g/L and pH of 5. The coatings prepared under the optimum technological conditions are uniform and compact, and the microhardness and corrosion resistance are increased significantly.