The work aims to extend service life and improve corrosion resistance of ink scraper. Ni-P coating and Ni-P/Al2O3 composite coating co-depositing nano Al2O3 were prepared in electro-brush plating method. Corrosion behavior of Ni-P coating and Ni-P/Al2O3 composite coating in 3.5% NaCl solution by means of potentiodynamic polarization curve, corrosion weight loss curve and AC impedance spectroscopy. Microstructure and composition of the two coatings before and after corrosion were analyzed with scanning electron microscope (SEM) and energy-dispersive spectroscope (EDS). Corrosion potential of Ni-P coating, which was codeposited with nano-Al2O3, shifted positively from ?0.318 V to ?0.237 V, and self-corrosion current density decreased from 6.04 μA to 5.75 μA since standard potential of namo Al2O3 was more positive than that of Ni, uniform distribution in coating led to positive shift of corrosion potential and formed corrosion microbattery with Ni-P alloy as anode and Al2O3 particle as cathode, and thereby promoted anodic polarization. After codeposition of nano Al2O3, the electrochemical reaction resistance Rct of Ni-P/Al2O3 increased from 1.066×104 Ω?cm2 to 2.864×104 Ω?cm2, double-layer capacitance Cdl decreased from 43.45 μF/cm2 to 27.36 μF/cm2. Compared with the Ni-P coating, the surface structure of the Ni-P/Al2O3 composite coating was more compact and the defects were less. In the process of corrosion, the phosphorus and oxygen elements were enriched on the surface of Ni-P coating to form a passive film which inhibited the corrosion. Codeposition of Al2O3 nanoparticles can effectively improve corrosion resistance of Ni-P coating.