The influence of two different surface treatments on the electrochemical activity of magnesium had been studied.The main process is respectively as follows:(1)cleaning with chromium anhydride then the nickel electroless plating (NEP); (2) cleaning with solvent then anodic oxidizing in acid solution (AOA).By adjusting the solution composition and treating time,film layers with different structure and thickness were formed.The Nyquist diagrams gotten from electrochemical impedance measurement show that the films have different equivalent circuits.The film of AOA treatment is equivalent to several parallel circuits of resistance and capacitance indicating the film might contain different property layers.