The epoxy/polyurethane coating has high electrical isolation, anti-corrosion and high adhesive bond strength with magnesium alloy substrate. The coating can effectively block or reduce the substrate erosion induced by water, oxygen as well as the corrosive ions such as , and . The mechanism and efficiency of corrosion protection of the polyurethane coating and epoxy/polyurethane coating on magnesium alloys were studied experimentally. The results indicate that both kinds of coatings improved the anti-corrosion property of magnesium alloy evidently. The anti-corrosion property of the epoxy/polyurethane coating is better than that of the polyurethane coating. The experimental results, which were obtained by the immersion tests in 3.5wt% NaCl solution, loss weight tests, salt spray tests, adhesive force tests, hardness tests, electrochemical tests and stereo microscope photos, definitely support the previous conclusions.