In order to explore the influence of nanoparticles on the antiwear and friction reducing properties of waterbased nano hydraulic fluid,a dynamic model of nano fluid between plates under shear flow conditions was built by taking waterbased Cu nano hydraulic fluid as an example.The LennardJones potential function,EAM(embedded atom model) and MCY were adopted to build potential model between atoms.The bearing capacity,antiwear and friction reducing properties of waterbased nano hydraulic fluid under different loads,different content of nanoparticles and different shear rates were studied.The results show that the bearing capacity increases with the increase of the content of nanoparticles.The friction between the walls decreases with the increase of the content of nanoparticles within certain range,however,the excessive content of nanoparticles leads to increased friction.The movement of nanoparticles under shear flow was explored by the molecular simulation.It is found that nanoparticles action is similar to the ball effect of ballbearings between the upper and lower metal walls in the simulation region.