Ti6Al4V alloys were treated by Ni+ implantation under different doses and energies to improve their biological frictional properties.The nanohardness was measured by Nano Indenter Ⅱ.Biological friction test was performed on MRTR multifunctional machine under the lubrication of sodium hyaluronate and with ZrO2ball and surface modified layers on Ti6Al4V as the friction pairs.Scanning electron microscope was used to observe the grinding crack.The results show that Ti2Ni is formed in the surface modification layer of Ti6Al4V.With the increasing of doses and energies of Ni+ implantation,the content of Ti2Ni in the surface modified layers is increased,the nanohardness of surface modified layers is increased and the friction coefficient is decreased,and the wear of surface modified layers is reduced in different degrees.Compared to the increasing of doses,the increasing of energies is more favorable to improve the biological frictional properties of surface modified layers of Ti6Al4V.