Based on the theory of GREENWOOD and TRIPP micro convex body contact,the mathematic model and entity model of the main bearings of internal combustion engine(ICE)were established considering the influence factors such as temperature,elastic deformation,etc,the relationship between main bearings lubrication performance and its surface roughness was studied.The results show that the film pressure and friction loss power are increased slightly,the oil film temperature changes little,because of relatively small asperity contact force.Rough surface of the bearing increases asperity contact pressure,causes the journal misalignment.With the increase of surface roughness,the oil film pressure is reduced,the thickness is increased,the rough peak contact pressure is increased.