Cr-N coatings were deposited on magnesium alloy by close field unbalanced magnetron sputtering technique (CFUBMS) with different bias. The microstructure, thickness, adhesion and wear properties of the coatings were characterized. The results show that the coatings are mainly composed of Cr(N) phase and a little Cr2N phase. The coating deposited with the bias of 60 V has higher hardness, well adhesion and wear properties. With further increasing the bias voltage, the coating hardness is enhanced; however, both the adhesion and wear resistance are reduced