Ti6Al7Nb alloys were implanted with 40 keV N+ and different implanting dosage, using in high energy ion implantation and enhanced deposition system. The torsional fretting wears of an un-treated and an ion implantation nitride Ti6Al7Nb alloy flats against Zr2O ball (with diameter of 25.2 mm) were carried out under a simulated physiological condition. Combined with the analyses of the frictional kinetics behaviours, and by means of X-ray diffraction, micro-hardness tester and SEM morphologies, the damage characteristics of the surface modification layer and its substrate were discussed in detail. The results show that the ion implantation nitride can improve the surface hardness of the alloy, its resistance of the torsional fretting wear is improved also