WC cemented carbide suffers severe wear in water environments. A novel carbon-based film could be a feasible way to overcome this drawback. In this study, a rare earth Ce-modified（Ti,Ce）/a-C:H carbon-based film is successfully prepared on WC cemented carbide using a DC reactive magnetron sputtering process. The microstructure, mechanical properties,and tribological behavior of the as-prepared carbon-based film are systematically investigated. The results show that the doping Ti forms Ti C nanocrystallites that are uniformly dispersed in the amorphous carbon matrix, whereas the doping Ce forms CeO₂ that exists with the amorphous phase in the co-doped（Ti,Ce）/a-C:H carbon-based film. The mechanical properties of this（Ti,Ce）/a-C:H film exhibit remarkable improvements, which could suggest higher hardness and elastic modulus as well as better adhesive strength compared to solitary Ti-doped Ti/a-C:H film. In particular, the as-prepared（Ti,Ce）/a-C:H film presents a relatively low friction coefficient and wear rate in both ambient air and deionized water,indicating that（Ti,Ce）/a-C:H film could feasibly improve the tribological performance of WC cemented carbide in a water environment.