Pure Ni and Ni－CeO₂ nanocrystalline coatings were prepared from a Watts－nickel electrolyte using ultrasonic－assisted pulse electro deposition. Effect of incorporating CeO₂ addition on their corrosion behavior in a 3.5%NaCl+1.5%HCl (mass fraction) solution was evaluated by electrochemical impedance spectroscopy (EIS) and equivalent electric circuits (EECs). Meanwhile, static immersion tests and the analysis of corrosion products were carried out. Experimental results indicated that the existence of CeO₂ phase in the Ni coatings promoted an effective dispersion strengthening after aged at 600℃ for 4 h in air, and also produced a continuous Ce－rich oxide sale acted as the passive layer covered on the coating surface to reduce pinholes or micro cracks that generated from hydrogen evolution reactions during electrochemical deposition, hence resulting in the decrease of localized corrosion or intergranular attack by Cl^-. Based on the observed results from potentiodynamic polarization curves, they exhibited an obvious passivation transition attached with a reducing corrosion current density by lower than 1.5 orders of magnitude of Ni－CeO₂ coatings (600℃) as relative to pure Ni. EIS measurements for pure Ni displayed a high frequency capacitive arc together with a middle－low frequency diffusion arc. While for the Ni－CeO₂ coatings, they displayed module of capacitive arc with a wide frequency area of phase angle close to 90° so as to confirm superior anti－corrosion property. During long－term static immersion tests in an acid NaCl solution, a small amount of Ce³⁺ released from CeO₂ phase were served as the corrosion inhibitors by means of making strong adsorption onto the exposed area for increasingcorrosion resistance. With the presence of CeO₂ addition, slightly uniform corrosion was observed on the surface of Ni－CeO₂ coatings as compared to severely pitting corrosion of pure Ni. According to the determination of corrosion products by XRD and XPS, both of their corrosion products were mainly composed of NiCl₂ and Ni(OH)₂, while some insoluble products of CeCl₃ and CeO₂ phase generated on the surface of Ni－CeO₂ coatings, thereby achieving such insoluble corrosion products covered on pitting holes of localized corrosion to preclude the exposed area from corrosive attack and diffusion behavior by Cl^-.