In this present paper, TiCN coatings were successfully fabricated by reactive plasma spraying, and the effect of heat-treatment of Ti/graphite powders on the microstructure and mechanical properties were studied. Results show that all coatings are consist of ternary TiCN main phase, small amount of TiOx and residual graphite phase. With the Ti/graphite agglomerates heat treatment temperature increasing from 0 °C to 900 °C, the apparent density and flowability of the agglomerates were improved, which is conductive to reduce coating porosity and further improve mechanical properties of sprayed coatings. Although all coatings shows an apparent scattering characteristic for Weibull distribution of Vickers micro-hardness, the coating sprayed using the agglomerates heat-treated at 700 °C exhibits a relatively even distribution. During heat treatment process, Ti particles would react with graphite particle to form TiC phase, especially for the temperature exceed 700 °C. In this case, the amount of ternary TiCN phases in the coatings would increase because of there is more graphite involved in Ti-graphite-N2 reactions. When the heat treatment temperature increase to 900 °C, obvious TiC diffraction peaks are observed in the agglomerates, but this would weak Ti-graphite-N2 reactions and the deposition deformation of the coating. Therefore, the C700 coating presents improved mechanical properties, such as high micro-hardness, good indentation toughness and well wear resistance as compared with other coatings, which is due to its dense microstructure and the relative high amounts of ternary TiCN phase.