Objective To study the microstructures, mechanical and tribological properties of Al2O3 micro-nano coatings. Methods Nanosized Al2O3 powders were deposited using atmospheric plasma spraying technique. Particle size distributed from 35 to 75 μm, consisted of nano-Al2O3, were obtained by spray drying. Micro-coatings of commercial Al2O3 feedstocks were also prepared as control. Microstructure of powders and coatings, as well as the worn surface of coatings, were characterized. Moreover, microstructure, mechanical and tribological behaviors of both nano and micro coatings were analyzed, respectively. Results Al2O3 nano-coatings showed a better interface bonding between the layers compared with Al2O3 micro coatings which resulted in great improvement of adhesion strength and microhardness of Al2O3 nano coatings. The friction coefficient of Al2O3 micro coating is 0. 41 while Al2O3 nano coating 0. 34 at the speed of 1000 r/ min and 750 g load. Conclusion Al2O3 nano coatings showed a better mechanical properties and wear resistance due to the excellent microstructure.