Abstract: TiN cermet coating was deposited on 45# steel substrate with model DZ-1400 electric-spark build-up welding machine, and the industrial pure titanium (TA2) was used for electrode and the industrial pure nitrogen for shielding and reactive gas. Surface morphology, microstructure and wear morphology of the coatings were investigated using model KYKY-2800 scanning electron microscope modeled. Phases of the coatings were analyzed using model D/max-RA X-ray diffractometer. Microhardness of the coatings was tested using model MH-6 hardness-testing device. The wear-resisting property of coatings was compared with 65Mn steel treated by the quenching and backfiring technology using the home-made abrasion machine. The feasibility was analyzed for reactive electric-spark build-up welding TiN cermet coating to be used for gear shaft restoration. The results indicated that excellent bonding between the coating and the carbon steel substrate was ensured by the strong metallurgical interface. The coatings were mainly made up of Ti coming from electrode, TiN ceramic particle reactive synthesized and Fe coming from substrate. The coatings were of good hardness and wear-resisting property. The experience of the gear shaft restoration indicated that the technology of reactive electric-spark build-up welding TiN cermet coating was feasible to repair the damaged shaft parts.