Nanoparticle reinforced nickel matrix composite coatings, such as n-Al2O3/Ni, n-SiO2/Ni, n-SiC/Ni and n-TiO2/Ni, were fabricated by brush plating technique. Hardness, wear resistance and contact-fatigue resistance of the composite coatings were determined, and strengthening mechanism of the composite coatings was discussed. Results showed that the composite coatings had superior properties to the Ni metal coating. Compared with properties of brush plated Ni metal coating, the composite coatings had hardness over 1.5 times and wear resistance capability of about 2.5 times. The strengthening mechanism of the composite coatings mainly included fine-crystal grain effect, nanoparticle dispersion effect and dislocation effect.