A ceramic coating was formed on AZ91D magnesium alloy by micro arc oxidation technology in aqueous solution containing silicate and phosphate. The phase compositions, surface, cross-sectional and wear track morphologies of coatings were analyzed by XRD, SEM and Laser Scanning Confocal Microscope (LSCM) respectively. Using the UMT-3 High Temperature Tribometer to study the friction and wear behaviors of coatings within 150 ℃. The results showed that the coatings’ mean friction coefficient firstly increased with temperature, when ambient temperature exceed 100 ℃ it began to reduce. While the coatings’ wear rate was much lower than that of magnesium alloy substrate and it reduced as temperature went up. The results indicated that micro arc oxidation coating had excellent wear resistance particularly at high temperature. Through the analysis of grinding cracks’ micro-structure at the load of 2N, the main wear mechanism of these coatings at different temperatures was all abrasive wear.