Al2O3-13%TiO2 coatings were prpared by plasma spraying with micron powder and nano powder on 45 steel. The microhardness and porosity of coating were tested and the microstructure was analyzed. The results show that: the nano-Al2O3-13%TiO2 coating has a large number of the integration semi-melted particles, while the micron coating has a significant layer structure. The nano-Al2O3-13%TiO2 coating has a higher vickers micro-hardness bonding strength and a lower porosity.