The foil stiffness characteristic of bump foil bearing is an important index to evaluate the bearing performance.In order to study the effect of friction on the stiffness of bump foil reasonably and comprehensively,the Euler beam model of bump foil was established,and an algorithm for determining the frictional state of bump foil was proposed.The constraint equation was adjusted reasonably according to the constraints of static frictional state and the dynamic frictional forcedisplacement relationship.It is found that the existence of friction increases the stiffness of foil,and the foil stiffness without slip is larger than that with slip.The effect of the number of elements on the calculation results was explored,and it is found that it has little effect on the results.The calculation results of the beam model were compared with that of the linear spring model and the experimental values in the literature.The results show that the calculated value of the beam model is closer to the experimental value,which verifies the accuracy of the beam model.