The work aims to investigate the influence of rare earth content on the structure and properties of Ti6Al4V alloy by plasma nitriding. Plasma nitriding of Ti6Al4V(TC4) titanium alloy was carried out by plasma surface modification technology. Rare earth with different contents were introduced as accelerating agents in the nitriding process to obtain strengthening layer on titanium alloy surface. Microstructure and phase composition of nitrided layer were observed and evaluated by SEM and XRD. Chemical components were detected by EDS. Microhardness was tested by Vickers microhardness tester. The friction and wear properties of the infiltration layer were tested by ball-disc friction and wear tester and three- dimensional profiler. The structure of plasma nitrided layer on TC4 alloy surface consisted of compound layer (δ-TiN phase) and diffusion layer (N-Ti solid solution mainly formed by diffusion of N atoms.). Rare earth could promote the diffusion of N into the matrix during nitriding process, thus increasing the nitriding speed, the thickness, the microhardness and the wear properties. The diffusion layer could smooth the hardness gradient between the titanium alloy matrix and the compound layer. When the flow rate of the rare earth content was 60 mL/min, the thickness of the nitride layer reached 155 μm and the surface mircohardness was 1275HV0.05. The friction coefficient was reduced to 0.27, and the wear rate was obviously reduced. The addition of rare earth elements in the plasma nitriding process can effectively increase the penetration rate and improve the hardness and the wear resistance of the nitriding layer.