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 CeO_2 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. 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) / aC: 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 films are systematically investigated. The results show that the doping Ti forms Ti C nanocrystallites that are uniformly. dispersed in the amorphous carbon matrix, and the doping Ce forms CeO 2 that exists with the amorphous phase in the co-doped (Ti, Ce) / aC: H carbon-based film. The mechanical properties of this (Ti, Ce) / aC : H film exhibit remarkable improvements, which could suggest higher hardness and elastic modulus as well as better as adhesive strength than to solitary Ti-doped Ti / aC: H film. In particular, the as-prepared (Ti, Ce) / aC: H film presents a relatively low friction coe fficient 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.