Black micro-arc oxidation (MAO) ceramic coatings were prepared on magnesium alloy in a silicate electrolyte; SEM, EDS and XRD were tested to analyze surface morphology, chemical composition and phase composition of ceramic coatings, Corrosion resistant in 3.5% NaCl aqueous solution of magnesium alloy before and after MAO treatment was evaluated by polarization curves and electrochemical impedance spectroscopy (EIS); the weight loss of magnesium alloy with black MAO ceramic coatings in 3.5% NaCl aqueous solution was studied through immersion experiment. The results indicated that, the black MAO ceramic coatings was composed by Mg、Al、Si、Cu and O; black MAO ceramic coatings could protect magnesium alloy substrate effectively; the corrosion resistant of black MAO ceramic coatings in neutral 3.5% NaCl solution was favorable.