Abstract: Pure titanium and Ti6Al7Nb alloys alloys were implanted by 50 keV N⁺ ions with different implanting dosage in high energy ion implantation and enhanced deposition system. Torsional fretting wear of un-treated and plasma implantation nitride titanium alloys flats against ZrO₂ ball (with a diameter of 25.2 mm) were carried out under a simulated physiological condition. With analyses of the frictional kinetics behaviors, the X-ray diffraction, Raman spectroscopy, 3-D profiler,SEM morphologies, the damage characteristics of the surface modification layer and its substrate were discussed in detail.The results show that the plasma implantation nitride can improve its surface properties and the resistance of torsional fretting wear can be improved obviously.The wear mechanism of the pure titanium and Ti6Al7Nb were oxidation wear and delaminlation, the ploughing of the modification layers.