In modern industry, using lubricating materials to reduce friction and wear has become an important means to improve the durability of mechanical components and improve mechanical efficiency. Among them, lubricating additives have been widely proved to be able to further improve the lubrication performance of lubricating medium, so it is necessary to study the tribological performance of lubricating additives. As lubricant additives, nanomaterials can effectively reduce the friction, improve wear resistance and extreme pressure properties of the based lubricant medium, and then improve the tribological properties of lubricated mechanical systems, which is of great significance for energy conservation, emission reduction and environmental protection. With special two-dimensional (2D) structure and superior thermodynamic and mechanical properties, graphene has attracted extensive attention in tribology research as lubricating materials. In recent years, a large number of graphene and its nanocomposites were prepared and studied as lubricant additives. Based on a large number of published literature, this paper summarizes the research results of graphene-related materials as lubricant additives in detail, including graphene and its derivatives, covalently bonded and non-covalently bonded organic functional graphene, graphene-based nanocomposites and the composites consisting of graphene and other 2D nanomaterials. The factors affecting the dispersion stability and friction and wear properties of graphene are analyzed. In addition, emphasis is put on the discussion of friction-reducing and anti-wear mechanisms of different functionalized graphene and graphene-based nanocomposites as lubricant additives. Finally, the problems and shortcomings of graphene and its nanocomposites as high-performance lubricant additives are discussed, and the future research trend of graphene and its nanocomposites is forecasted.