Abstract: Micro/nano surface structures will affect the fluid flow behavior near the wall in the micro-scale flow, so that the entire fluid flow behavior and lubrication property in micro channel may be changed in which the surface micro/nano structures act as a porous medium layer. Under continuous boundary conditions, the velocity and pressure distribution can be solved using Brinkman equation as the momentum equation of porous region, coupled with Navier-stokes equation which is momentum equation of free region. When assuming the normal load capacity of oil film is constant, permeability characteristics and location of surface micro/nano structures have a great influence on fluid flow behavior near the wall, thus change oil film thickness and friction coefficient of hydrodynamic lubrication. The results provide a theoretical reference of micro-scale flow and lubrication, the surface of which is not completely smooth.