The effects of graphene as an additive of nhexadecane(C16H34)lubricating oil on the lubricating properties of silicon nitridebearing steel(Si3N4-GCr15)friction pair were studied by molecular dynamics method.The effects of graphene mass fraction,pressure and shear rate on the van der Waals energy,shear stress and solid film thickness of the film lubrication zone were analyzed.The results show that an appropriate amount of graphene can improve the van der Waals energy of the lubrication region,increase the thickness of the solid film,reduce the shear stress of the friction pair of Si3N4-GCr15,and reduce the friction between the friction pairs.When the graphene molar mass fraction is 2.5%,the van der Waals energy in the lubrication region is the largest and the shear stress is the smallest.When graphene is added,van der Waals energy,shear stress and solid film thickness change smoothly with changes in pressure and shear velocity,but they have a large fluctuations when graphene is not added.It can be concluded that graphene as an additive changes the variation of van der Waals,shear stress and solid film thickness in the lubrication zone under influence of pressure and shear velocity.