Abstract: TiN/Ti composite coating was deposited on TC4 titanium alloy substratewith electric-spark deposition machine modeled DZ-1400, which the commercial pure titanium (TA₂)was used for electrode and the commercial pure nitrogen gas was employed as shielding and reacting atmosphere.Effects of the parameters as discharge capacitance, output voltage and impulse frequency on X-ray diffraction (XRD)patterns of TiN/Ti composite coatings were analyzed X-ray diffractometer.The microhardness of coatings was tested with microhardness instrument modeled MH-6.The microstructures and wear morphology were investigated by scanning electronic microscope (SEM).The friction coefficient and wearing capacity lost were tested by ball-pan wear and tear gauge modeled MS-T3000.The results indicated that TiN, a new phase, was synthesized by the element of Ti and N, which come from electrode, substrate and shielding gas respectively and the coatings are mainly composed of Ti and TiN.The XRD patterns were changed with the change of discharge capacitance, output voltage and impulse frequency.An excellent bonding between the coatings and substrates is ensured by the strong metallurgical interface.The highest microhardness of coating reaches to 1 388 HV0.1, which is about six times more than that of the substrates. The friction coefficient of the coatings is small and the wear resistance is excellent.