A duplex treatment of plasma Zr-alloying and plasma nitriding was used to improve the tribological properties of Ti-6Al-4V. The microstructure of the Zr-N composite(alloyed) layer formed on Ti-6Al-4V and its hardness, friction and wear properties were investigated by using OM, SEM, GDOES, EDS, microhardness tester as well as ball-on-disk tribometer. The results of microstructural analysis show that the alloyed layer is compact and uniform and is mainly composed of ZrN, TiN_(0.3) and AlN. A very tiny adhesive and slight oxidation wear is the primary wear mechanism for the modified Ti-6Al-4V. The tribological property is improved significantly after the duplex treatment. The good combination of antifriction and wear resistance for modified Ti-6Al-4V is mainly attributed to the higher surface hardness of metal nitrides formed on the surface and enhanced supporting of the Zr-diffusing layer. A duplex treatment of plasma Zr-alloying and plasma nitriding was used to improve the tribological properties of Ti-6Al-4V. The microstructure of the Zr-N composite (alloyed) layer formed on Ti-6AI-4V and its hardness, friction and wear properties were investigated by using OM, SEM, GDOES, EDS, microhardness tester as well as ball-on-disk tribometer. The results of microstructural analysis show that the alloyed layer is compact and uniform and is mainly composed of ZrN, TiN_ (0.3 ) and AlN. A very tiny adhesive and slight oxidation wear is the primary wear mechanism for the modified Ti-6Al-4V. The tribological property is improved significantly after the duplex treatment. The good combination of antifriction and wear resistance for modified Ti-6Al -4V is mainly attributed to the higher surface hardness of metal nitrides formed on the surface and enhanced supporting of the Zr-diffusing layer.