TC4 titanium alloy was treated by ion nitriding. The structure of nitriding layer was analyzed by scanning electron microscopy. The depth and microhardness of nitriding layer were measured. The frictional properties of titanium alloy before and after nitriding were compared by friction test. The results show that the ion nitriding technology can form a stable nitriding layer with a depth of up to 20μm and a surface hardness of 560 HV0.2. At the same time, after nitriding, the wear resistance of the titanium alloy surface is improved. And the coefficient of friction between the friction pair is reduced.