The tribological properties of diamond-like carbon (DLC, a-C), amorphous carbon nitride (a-CNx), transition metallic nitride (TiN, CrN) and correspondingly modified nano-composite films under water lubrication are reviewed. The influence of microstructure, architecture, element doping, counterparts and friction parameters on the tribology and wear mechanisms of nano-composite films under water lubrication are analyzed and elucidated spontaneously. It is clear that nano-composite films present excellent tribological properties under water lubrication, which are closely related to the composition, architecture, mechanical properties and the physic-chemical properties of tribo-materials. In general, as compared with transition metallic nitride films, DLC and a-CNx exhibit lower friction coefficients and wear rates under water lubrication due to the formation of transfer layer and hydrated lubricating layer. Secondly, nano-composite films exhibit low specific wear rate due to the protection of hydrated layer when mating materials are hydrated easily. Finally, moderate load and velocity are also key factors to optimize tribology under water lubrication if the film is not peeling and failure. The study provides some references for the application of film in water lubrication equipment and the future of nano-composite films under water lubrication is proposed synthetically.