A　highly　corrosion-resistant　and　active-protection　composite　coating　was　prepared　using　layered　double　hydroxides　(LDH)　layer　and　micro-arc　oxidation　(MAO)　to　further　improve　the　anti-corrosion　property　of　Mg　alloy.　MgCr-LDH/MAO　composite　coating　was　prepared　through　in-situ　growing　LDH　layer　including　NO3-　on　the　surface　of　MAO　coating.　The　morphology,　composition　and　microstructure　of　the　MgCr-LDH/MAO　composite　coating　were　characterized　by　XRD,　XPS,　FT-IR,　SEM,　and　the　interaction　between　LDH　and　original　MAO　coating　was　investigated.　The　anti-corrosion　properties　of　the　MgCr-LDH/MAO　coating　were　tested　through　immersion　in　3.5%　NaCl　(mass　fraction)　solution　and　electrochemical　experiments.　The　results　show　that　the　LDHs　form　a　dense　sheet-like　layer　on　the　original　MAO　coating　surface,　which　can　effectively　cover　the　inherent　defects　of　MAO　coating,　and　LDH　layer　is　preferentially　formed　in　the　pores　of　original　MAO　coating.　LDHs　do　not　damage　the　original　MAO　coating　during　the　growth　process,　and　the　adhesion　of　LDH　layer　and　MAO　layer　are　strong　and　stable.　The　composite　coating　shows　the　optimum　corrosion　protection,　since　MgCr-LDH　layer　growing　on　the　original　MAO　coating　can　hinder　the　penetration　of　chloride　ions　and　effectively　adsorb　a　large　number　of　NO3-　to　exchange　Cr　in　corrosion　solution.