Fatigue cracking is one of the common diseases of orthotropic steel bridge deck, which is closely related to the excessive stress amplitude of key details caused by the large stiffness of bridge deck pavement. Using UHPC to improve the stiffness of bridge deck pavement is an important means to alleviate fatigue stress. In order to study the fatigue performance of key details under the action of actual traffic flow, taking a cable-stayed bridge of highway spanning Luohe River as an example, the analysis on the stress influence surface of structural details of the steel-UHPC composite paved orthotropic steel deck is carried out, and the loading analysis on the structural details is carried out by the actual traffic flow of monitoring records to obtain its stress spectrum. Based on Miner fatigue damage equivalent principle, the maximum stress amplitude, equivalent stress amplitude and fatigue loading times are calculated and obtained. The results show that UHPC to reinforce the deck pavement can significantly reduce the stress of structural details, improve the mechanical behavior of structural details, and significantly reduce the stress amplitude of structural details on the deck slab so that the maximum stress amplitude recorded by the structural details of longitudinal rib - deck slab weld and the deck slab butt weld is less than the constant amplitude fatigue limit.