Controlling the friction in the rolling bite is important to the cold rolling of metal strips.The main difficulty is that the strip surface deformation in a rolling process is associated with mixed lubrication which has not been properly understood.This is because the interaction of a roll surface with a metal strip always involves different types of contacts : solid-solid ( asperity-asperity ),solid-liquid ( asperity-lubricant ) and lubricant film interactions.Observations have also shown that the contact deformation in a rolling bite determines the zones of rolling,characterised by a number of sub-regions subjected to elastic,plastic,or hydrodynamic deformation;but the instant tribo-property of lubricant with a work material during rolling is unclear.This paper presents a novel three- dimensional analysis based on the finite element method to investigate the mixed lubrication in the cold rolling of metal strips.The key innovation here is the introduction of the concept of an equivalent interfacial layer to integrate the Reynolds equation with the deformation of surface asperities of a strip.This,on one hand,facilitates the characterization of the rolling pressure and shear in relation to the properties of the lubricant applied;and on the other hand,this enables to capture the microscopic roll-strip interface deformation associated with the surface asperities randomly distributed.Equally importantly to the practitioners in rolling production,the analysis can be realized effectively by using the commercially available explicit finite element method.The result of this study shows that the simulation using the new modeling method can reflect very well the experimental measurements in cold rolling processes.