Elastohydrodynamic lubricating (EHL) oil film has remarkable elasticity and damping effect,which has great impact on the dynamic performance of high pair contact parts such as gear,rolling bearing,cam etc.However,the mechanism,especially the mathematical formulation on the stiffness and damping of EHL friction pairs remains unclear.A numerical method was used to solve the tribology and dynamics coupling model of line contact EHL friction pair,and the hysteresis loop of the EHL friction pair under harmonic excitation was obtained.Through the hysteresis loop,the stiffness and damping of line contact EHL friction pair were identified.The effects of load,entrainment speed,material parameters on the stiffness and damping of line contact EHL friction pair were studied by means of variable control,and the influence mechanism of load and entrainment speed on the stiffness and damping of EHL friction pairs was analyzed.The results show that the stiffness and damping of the line contact EHL friction pair increase with the increase of load and decrease with the increase of entrainment speed.The stiffness and damping formulas of line contact EHF friction pair were fitted based on a large number of numerical solutions.It is found that the load has the most significant impact on the stiffness and damping of the EHL friction pair,and the change amplitude of the stiffness of EHL friction pair is greater than that of the damping with changes in load,speed,and material parameters.The accuracy test of the fitting formula shows that the relative error between the calculated results of the fitting formula and the numerical solutions is less than 10% in a wide range of parameters.