Abstract: The stiffness of oily interfaces can be divided into two parts,solid contact stiffness and liquid oil film dynamic stiffness;meanwhile the two parts are shunt connection.Using fractal theory of contact,the model for normal solid contact stiffness of the oily interface was established,which is related to the area of actual solid contact surface;on this basis,the area of the oil-filled contact is the difference between nominal contact area and actual solid contact area,and the model for oil film normal dynamic stiffness of porous oily material fixed joint interface was set up based on the average flow of generalized Reynolds equation.The model for normal comprehensive dynamic stiffness both can be easily obtained considering the shunt relationship.Through simulation and comparing to previous experimental results,the correctness of the modeling method was verified.Resultsshow that the stiffness of joint interfaces can be effectively improved with oil media filled into the interface.In addition,using of oily porous material,that is,self-lubricating material is proved to be an effective proposal for oil-filling between the joint interfaces.