Although titanium(Ti)based medical devices have been used clinically for more than 30 years,there are still weaknesses for them that need to be resolved.The lacks of osteoconduction and osteointegration in bones for long-term survival often occur and lead to failures of implantations [1].Therefore A challenge for Ti-based implants is incorporating the osteointegration,as well as an enhanced bioactivity for bone healing and regeneration,which will improve the implant-host interactions.Magnesium based metals have been increasingly studied in the past decade,owing to their biodegradability and multiple biological activities [2].It was found that magnesium could positively influence the bone tissue growth,and thus improve the bone healing and reconstruction [3].The biodegradable magnesium employed as coating can also be appropriate for medical implants,which is expected to promote drug-enhancing osteointegration and reduce implant infection compared with conventional metals and coatings used today.In this study,a bio-functional magnesium coating was fabricated on Ti6Al4V alloy by arc-ion plating,which was proved to have fine grain size and high coating/substrate adhesion in comparison with other PVD methods [4].Microstructure,morphology and composition of the magnesium coating were investigated by means of SEM,EDS and XRD.In vitro degradation and ions releasing were measured after immersion in simulated body fluid.Furthermore,animal implantation tests were conducted to evaluate the related cell attachment,viability and bone response in vivo.A uniform magnesium coating was successfully deposited on the surface of Ti6Al4V alloy.With increase of immersion time,magnesium ions were gradually released due to biodegradation.Both in vitro and in vivo experiments proved that the magnesium coated titanium alloy has a better biological activity on proliferation and differentiation of BMSCs.After implantation the magnesium coating could promote the new bone formation and had positive effects of osteoconductivity and osteogenesis,thus indicating its great potential for orthopedic applications.