According to the geometry configuration and contact state of the fretting contact pairs,with the cylindrical foot fretting bridge and flat sample as the research object,the finite element model of fretting damage was set up by ANSYS software.The influence of stress intensity and stress intensity amplitude on fretting crack initiation characteristics was analyzed.SWT critical plane approach was used to predict the micro crack initiation position,and the predicted result was compared with the experimental result.The results show that there is stress concentration in the contact region of fretting bridge and plane sample.The location of maximum stress intensity amplitude is at the center of contact area and a little biased outboard of bridge foot,where the strain is the maximum under the axial load,which results in the initiation crack.Crack initiation position predicted by SWT critical plane approach is consistent with the location of maximum stress intensity amplitude,and consistent with the experimental results.