The work aims to improve corrosion and wear resistance of organic coating on magnesium alloys. Ni+C composite film was first prepared on the surface of GW83 magnesium alloy by combining unbalanced magnetron sputtering ion plating and chemical plating. The surface morphology and composition and structure of the coating were analyzed by using SEM observation and Raman spectrometer. Corrosion resistance of the composite carbon film coating was evaluated by performing electrochemical tests and post-dipping inductively coupled plasma atomic emission spectrometry (ICP-AES) measurement. Meanwhile, wear longevity of the Ni+C composite coating was obtained by performing friction-wear test. The Ni+C composite coating featured in dense and uniform coating, extremely low surface porosity and surface carbon layer of graphite-like film containing numerous disordered structures. Compared with GW83 magnesium alloy, since the Ni+C composite coating was present, corrosion potential (Ecorr) in 3.5wt% NaCl solution improved by 301 mV, while the corrosion current density decreased from 186 μA/cm2 to 11 μA/cm2. The post dipping ICP-AES test revealed that the Ni+C coated magnesium alloy GW83 featured in less metal ion release. The friction-wear test showed that wear longevity of Ni+C composite coating was 7000 s, and thus the wear longevity was prolonged remarkably compared with the substrate of magnesium alloy. Corrosion resistance of the magnesium alloy can be greatly improved by Ni+C coating due to the thick nickel interlayer and dense surface carbon layer in the Ni+C composite coating. Furthermore, wear longevity of the magnesium alloy substrate can be effectively prolonged by coating Ni+C composite as a result of mechanical support by the thick Ni interlayer.