Nano-SiO2 particles strengthened Ni-based composite coating was designed and prepared on steel substrate. The structures and nanoparticle content of the nano-SiO2/Ni composite coating were determined by SEM,EDS and TEM; and the micro mechanical properties were tested by nano-indentation technique. The results show that 56 % of particles in the solution are dispersed in size of less than 100 nm, the content of nanoparticles co-deposi ted in the coating doubles and structure of the coating is more compact and uniform than that of Ni coating. NanoSiO2/Ni coating exhibits excellent micro mechanical properties, and the nanohardness and elastic modulus are 7.81 GPa and 198 GPa, respectively, which are attributed to finer crystal strengthening, dispersion strengthening and high-density dislocation strengthening of nano-SiO2 particles to the composite coatings.