The purpose of this paper is to study the effect of Al2O3 content on friction and wear properties of Al2O3-Ni composite coating.The 30wt.%Al2O3-70wt.%Ni, 50%wt.Al2O3-50wt.%Ni, 70wt.%Al2O3-30wt.%Ni composite coatings which contained 30%, 50% and 70% Al2O3 were deposited on the 6082-T6 aluminum alloy surface by air plasma spraying. The microhardness, friction and wear properties of the three coatings were compared and the phase composition of the original powder and the coating, the coating microstructure, wear morphology and wear mechanism were analyzed. Part of the original powder of a-Al2O3 phase were transformed into a new phase of γ-Al2O3 under quench condition. Various diffraction peaks in the coating showed obvious broadening phenomenon. Meanwhile, the amorphous phase of Al2O3 generated. The three kinds of samples were composed of the substrate, the priming coating and the coating. There was an obvious interface between the substrate and the priming coating. While the interface between the priming coating and the coating was not obvious because of its similar chemical composition. The good bonding formed between the layers. The microhardness of the coating was significantly higher than the substrate, which was about 4~5 times of the substrate. What’s more, it increased with the increase of Al2O3 content. The friction coefficient, wear width and wear rate decreased with the raising of Al2O3 content under the test condition. Compared to the 30wt.%Al2O3-70wt.%Ni coating, the friction coefficient and the wear rate of the 70wt.%Al2O3- 30wt.%Ni coating reduced by 13% and 66.7%, respectively. The 30wt.%Al2O3-70wt.%Ni coating had the most serious wear, which with obvious peeling on the surface of wear scar, while 50wt.%Al2O3-50wt.%Ni coating and 70wt.%Al2O3-30wt.%Ni coating produced a large number of "orange dermatoid" oxide. The wear mechanism was a mixture of oxidation wear and adhesive wear. The wear resistance of Al2O3-Ni composite coating can be improved by increasing Al2O3 content.