Abstract: Micro-arc oxidation technology was used to prepare a dense ceramic film on the surface of AZ91D magnesium alloy in NaAlO2-Na3PO4 composite electrolyte system, and then the impacts of doped nano-TiO2 on the microstructure, phase composition, corrosion resistance and friction and wear property of the film were analyzed. The results show that the micro-arc oxidation film prepared without nano-TiO2 powders had a loose and porous surface, and was composed of MgAl2O4, Mg3(PO4)2, MgO and Mg, in which the MgAl2O4 phase accounted for the most. In addition, the surface of micro-arc oxidation film became dense and a new phase of TiO2 appeared after adding nano-TiO2 powders into the electrolyte in preparation. Compared with the matrix of AZ91D magnesium alloy, the corrosion resistance and abrasive resistance of two oxidation films all increased significantly, especially for the film doped nano-TiO2 in preparation, which had the best corrosion resistance and abrasive resistance.