The fatigue mechanism at the connection between longitudinal ribs and diaphragm of orthogonal anisotropic steel bridge panel is complicated and difficult to analyze. In order to address this problem, the area around the curved opening of diaphragm and U-rib and the weld end of diaphragm is taken as the research location, and the stress distribution law in the area is combined with the in-depth analysis of the stress mechanism to find out the fatigue susceptibility point in this area. Taking the fatigue stress of the construction details as the control index, we propose the construction forms to reduce the fatigue stress such as variable thickness transverse spacer, double internal spacer and reverse arc notch at the connection between the transverse spacer and longitudinal ribs, etc. After the finite element calculations, the results show that: the variable thickness transverse spacer and the double internal spacer have an obvious effect on the fatigue at the arc openings and the end of the weld seam, respectively, the reverse arc notch makes the geometrical linearity smoother and reduces the stress concentration caused by geometrical discontinuities. Geometrical discontinuities, which can significantly reduce the fatigue stresses in the above two types of fatigue details.