Magnesium alloys exhibit great application potential in industries such as automotive, electronics, aerospace and others. But poor wear resistance and corrosion resistance have restricted their actual uses. In this study, a CrN film had been prepared on magnesium alloy AZ91 by arc-glow plasma depositing. The composition and microstructure of the coating had been analyzed by X-ray diffraction (XRD) and glow discharge spectrum (GDS). The morphology of CrN film has been surveyed through scanning electronic microscopy (SEM) and atom force microscopy (AFM). The wear behavior was investigated through ball-on-disc test. The corrosion behavior in 5 wt% NaCl solution was also studied. The results indicate that the specific wear ratio decreases greatly and the corrosion potential also increases relatively comparing to AZ91 matrix.