Abstract: Different thickness nano-graphenes were prepared and characterized by scanning electron microscopy and transmission electron microscopy. Friction and wear properties of water-dispersing system of graphene were investigated using an multi-functional reciprocating friction and wear tester in ambient condition. The morphology, elemental composition, and chemical state of typical elements on worn steel surfaces were analyzed by scanning electron microscopy with energy dispersive spectrum, X-ray photoelectron spectroscopy and the lubrication mechanism of water-dispersing system of graphene was explored primarily. Results indicate that the thickness of graphenes varied from 10 to 180 nm. Graphene possessed good friction-reducing and anti-wear properties by changing wear mechanism of pure water from severe adhesive wear and abrasive wear to abrasive wear. The main reason was that adsorption anti-friction layers and tribochemical films were formed on the worn surface lubricated with the water-dispersing system of graphene. Anti-friction layer and tribochemical film inhibited the oxidation of Fe and reduced friction and wear.