Diamond-like film (DLC) with Cr as transition layer was prepared on the surface of magnesium base alloy by plasma enhanced chemical vapor deposition (PECVD) to improve the corrosion resistance of high performance lightweight structural materials magnesium base alloy. The surface morphology of Cr/DLC films was characterized by scanning electron microscopy (SEM) and atomic force microscopy. The composition of Cr/DLC films was analyzed by energy dispersion spectrometer (EDS). The composition and structure of Cr/DLC film were characterized by Raman spectroscopy. Salt spray corrosion (3.5 wt % NaCl), polarization test and contact Angle test were used to evaluate the corrosion resistance of the samples.The results show that the Cr/DLC film prepared on magnesium alloy matrix by PECVD method has dense microstructure, enhanced hydrophobicity and reduced corrosion rate, which can effectively improve the corrosion resistance of magnesium alloy and provide a theoretical basis for promoting the engineering application of magnesium alloy.