Objective To study the microstructure, microhardness as well as dry sliding wear and friction behavior and mechanism of plasma sprayed TiN/ TiO composite ceramic coating under different conditions. Methods TiN/ TiO ceramic coating was prepared on 45# steel by reactive plasma spraying technology. Phase composition of the coating was analyzed using X-ray diffraction (XRD) and the microhardness was measured by a hardness tester. The wear and friction behavior of TiN/ TiO composite ceramic coating was studied through wear and friction tests, the wear and friction morphology was observed, the composition of the wear surface was tested, and the wear mechanism of TiN / TiO composite ceramic coating was discussed. Results The coating was even and dense with obvious layered structure and an average thickness of 350 μm. The porosity of the coating was 4. 3% and the hardness was 1444HV0. 1. Under the conditions of rotational speed at 370 to 1102 r / min and load at 30 to 50 N, the friction coefficient ranged from 0. 0963 to 0. 2778 and the wear mass loss was from 1. 32 to 6. 8 mg. Besides, the friction coefficient decreased with increasing load while the wear mass loss of the coated samples had an increasing trend with the increasing load and rotational speed. Conclusion The coating prepared by plasma spraying was dense with high microhardness. When the load and rotational speed were low, it had excellent wear resistance. However, the wear resistance decreased with increasing load and rotational speed. The main wear mechanisms of the coating were abrasive wear and adhesive wear.