The present paper studies the effect of creating a fillet on fretting fatigue strength of an axle, using different multiaxial fatigue criteria and fretting fatigue damage parameter. Finite element method is applied to obtain stress and strain in the axle and the results obtained from modeling are compared with the experimental test data available in literature. The results show that fretting fatigue strength of the axle and fracture area depends on the ratio of  diameter to fillet radius. Multiaxial fatigue criteria is almost capable of estimating the fatigue strength of the axle . However; the results obtained from investigating fretting fatigue damage parameter are almost in accordance with the results of experimental data and consequently fretting fatigue damage parameter can be appropriately used as a criterion for estimating fretting fatigue strength of the axles.