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To improve the wear resistance of titanium alloy parts used in the engineering applications, in-situ formed Ti(C,N) particles reinforcing Ni-based composite coatings are fabricated on Ti6Al4V alloys by the laser cladding technique using Ni60, C, TiN, and small amounts of CeO2 nanoparticles mixed powders as the pre-placed materials. Firstly, the formation mechanism of Ti(C,N) particles as a reinforced phase in the coating is investigated. Then, the influences of CeO2 nanoparticles on microstructures and wear resistance of the coatings are analyzed. It is indicated that the large Ti(C,N) particles form around TiN particles, and the small Ti(C,N) particles form through independent nucleation. CeO2 nanoparticles play important roles in increasing the nucleation rate and improving the precipitation of Ti(C,N), hence the microstructures and wear resistance of the coatings are apparently improved after adding CeO2 nanoparticles. It is observed that the 1 wt % content of CeO2 additive in the pre-placed powders is the best choice for the wear resistance of the coatings.