Magnesium Alloys are of low density, high specific strength and high strength, leading to much application prospect in industry and civilian use. However, the alloys are restrictedly used because of easy corrosion. In this paper, The Organic coatings on Magnesium Alloys are made. The electrochemical properties of organic coatings are researched by scanning electron microscope (SEM), stereoscopic microscope and electric-chemistry Work station. The research results show that the curves of open-circuit current to time and Tafel polarization shuffle more for the Pu and ER/PU coatings than for base alloy. With addition of the coating, the magnesium alloy has much low corrosion current density (icorr) and high polarization resistance (Rp), and then its Anti-corrosion Property is evidently improved.