The work aims to study the effect of graphene concentration on the growth and corrosion resistance of micro-arc oxidation ceramic coating of AZ91D magnesium alloy. Graphene dispersion was obtained by ultrasonic dispersion and added to the zirconium salt electrolyte to prepare the micro-arc oxidation ceramic coating on the surface of the magnesium alloy by micro-arc oxidation technique. The microstructure of the ceramic coating was analyzed by SEM and EDS, and the phase composition of the ceramic coating was analyzed by XRD. The polarization curves of the ceramic coating in 3.5%NaCl solution were measured by electrochemical workstation, and the corrosion resistance was analyzed. With increasing graphene concentration, the C content in the micropores of the ceramic coating firstly increased and then decreased, and the C content outside the micropores increased. The pore diameter of the ceramic coating and surface roughness decreased firstly and then increased. The porosity increased, but the thickness hardly changed. Moreover, the concentration of graphene had no effect on the phase composition of the ceramic coating, and the main phase composition was MgF2, ZrO2, MgO and Mg2Zr5O12. Compared with the sample without graphene, the corrosion current density was reduced by 1~2 orders of magnitude and the polarization resistance was increased by 1~2 orders of magnitude. When the concentration of graphene was 0.15 g/L, the pore diameter of the ceramic coating was the smallest, the corrosion current density was the smallest of 9.46×10-7 A/cm2, and the polarization resistance was the largest of 1.95×106 Ω?cm2. Thus, the coating had the best corrosion resistance. A certain concentration of graphene can reduce the micropore diameter of micro-arc oxidation ceramic coating, increase the porosity of ceramic coating and improve the corrosion resistance of ceramic coating.