Objective Vacuum pulse nitriding treatment at different pressure was applied to TC4 titanium alloy to improve surface hardness and wear resistance. Methods The microstructure and properties of hardened layer were analyzed by metallurgical microscopy, X-ray diffraction (XRD), microhardness tester and wear testing machine. Results The surface composite modified layer composed of TiN, Ti2AlN and Ti3Al was obtained by vacuum nitriding treatment of TC4 titanium alloy. Low nitriding pressure led to the low number of surface nitrides and the low thickness of the nitriding layer. With the increase of pressure, the number of nitrides increased, the surface hardness and wear resistance also increased. The surface hardness reached the maximum value at 0. 015 MPa. The surface hardness of nitrided TC4 titanium was 1100 ~1200HV, and the thickness of the effective hardened layer reached 50 ~60 μm. With further increase of nitriding pressure, the microstructure became loose, the surface hardness and wear resistance began to decrease. Conclusion Vacuum pulse nitriding treatment under suitable pressure and suitable concentration of N could increase the surface hardness of titanium alloy and improve its wear resistance.