The corrosion resistance of the graphite-like carbon coating on the cast GW93 magnesium alloy deposited by non-equilibrium magnetron sputtering was investigated through electrochemical methods as EIS and the Tafel polarization curves validated by agravity.Microstructure was observed by SEM and to analyze the influence on corrosion resistance.The results show that the composite coating is composed of chromium layer

transition layer and carbon layer.The growth modes of the coating are characterized by island structure.The graphite-like carbon coating can improve the corrosion resistance of the GW93 magnesium alloy as a result of improving the EIS to 5.0×1019 Ω and the self-corrosion potential to-0.940 V with background vacuum degree of 8.8×10-3 Pa.The background vacuum degree is a important factor influencing the corrosion resistance of graphite-like carbon coating

where corrosion resistance of the coating is improved increasingly with the increasing in background vacuum degree.