Abstract: An environmentally friendly anodizing process for AZ31 magnesium alloy was developed.The factors including components of the electrolyte,electrical parameters,controlling methods,process of sealing and electrolyte temperature that affect the film forming process and the properties of the film were analyzed.High corrosion resistant and compact anodized films were formed on AZ31 magnesium alloy by anodizing in environmentally friendly electrolyte composed of KOH,Na2B4O7,Na3PO4 and addictives.The properties of the anodized film were greatly affected by the composition of the electrolyte and the corrosion resistance of the anodized films was enhanced by sealing process.