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The composite electronic brush plating technique is facilitated to prepare the alloy nanocomposite plating with different nano-Al2O3 particles content. The effects of nanoparticles content in the electrolyte on the deposition rate, nanoparticles content, microhardness and tribological property of composite coatings are mainly discussed, measured by scanning electron microscopy, microhardness tester and attrition testing machine. It is found that, with the increase of nano-Al2O3 particles content in the solution, the deposition rate of coatings drops, the surface morphology of plating becomes flat, the microhardness is firstly enlarged and then decreased，wear scar depth is firstly reduced and then increased, friction coefficient is firstly reduced and then improved. When the nano-Al2O3 particles concentration in the electrolyte is 20g/L, the coating reaches its optimized structure and performance.