Abstract: The fatigue strength of bolts can be improved by rolling strengthening the thread bottom, and the rolling parameters directly affect the improvement of fatigue strength. In order to explore the influence of different rolling depths on the fatigue strength of bolts, the thread bottom was strengthened by rolling. The effects of different rolling depths on the fatigue resistance of 35 Cr2 Ni4 MoA bolts were studied by means of tensile fatigue test, fracture analysis, surface morphology analysis and surface roughness analysis. The test results show that the fatigue strength of the bolt first increases and then decreases with the increase of rolling depth. The lifting effect is best when the rolling depth is 0.08 mm, which is 31.57%higher than that of the non rolling bolt, and the surface roughness is only 0.414 μm. The research has guiding significance for formulating reasonable rolling parameters and provides technological support for anti fatigue manufacturing of bolts.