Al2O3-13%TiO2 ceramic coating was deposited on AZ31 magnesium alloy by plasma spraying. The microstructure of the coating was examined by means of SEM and XRD, the hardness of the coating was examined. The corrosion resistances of AZ31 magnesium alloy with and without ceramic coatings in immersing in 5%NaCl salt solution were compared and studied by polarization curve and immersing corrosion test. The results show that the hardness and the corrosion resistance of AZ31 magnesium alloy with ceramic coatings are superior to that of AZ31 magnesium alloy. But the corrosion of AZ31 magnesium alloy with ceramic coatings becomes more serious than that of magnesium alloy.