Magnesium lithium alloy is a metal structural material with excellent comprehensive performance, which has broad application prospects in fields such as shipborne aircraft. However, the poor wear and corrosion resistance of magnesium lithium alloy in marine environment greatly limits its application and promotion. In addition, the engineering application of magnesium lithium alloy also needs to meet the requirements of decoration, absorption or shielding of stray light. A black micro arc oxidation coating was prepared by adding two colored salts, copper pyrophosphate (Cu2P2O7) and cobalt sulfate (CoSO4) to the electrolyte. The resulting coating exhibited numerous defects such as microcracks. The microstructure and phase composition of the micro arc oxidation (MAO) coating were improved by adjusting the pulse frequency to enhance its wear and corrosion resistance in marine environment.