Aimed at the contact stiffness of the joint surfaces in mixed lubricated contact,an equivalent thin-layer model of the rough surface contact stiffness in mixed lubricated contact was established.The total stiffness of the contact interface was equivalent to the sum of the solid contact stiffness and the lubricant contact stiffness,and the effects of surface topographies and lubricant types on normal contact stiffness under varying real contact area were studied.The proportion of solid stiffness and lubricant stiffness from the total normal stiffness was also discussed.The results show that the normal contact stiffness of the rough surfaces increases with the increase of the normal load,and the mixed lubrication contact stiffness is greater than the dry contact stiffness.At the initial contact,the normal contact stiffness is sensitively dependent on the lubricating properties.With the increase of the real contact area,the influence of surface topography on the contact stiffness becomes more obvious.