<p>This study systematically investigates the effects of thermal exposure (80–240 °C, 5&#xa0;h) on the microstructure evolution and fatigue performance of T74-treated 7085 aluminum alloy, focusing on establishing quantitative microstructure-property relationship. Experimental results demonstrate that while grain size remained stable across the investigated temperature range, significant precipitate coarsening occurred above 120 °C. As thermal exposure temperature rose to 240 °C, the average precipitate radius increased by 215% (from 3.9 to 12.3&#xa0;nm) accompanied by substantial degradation of mechanical properties: tensile and fatigue strength decreased by 31.8% and 42.1%, respectively. Microstructure-property correlation analysis elucidated the underlying mechanism, attributing the performance degradation to reduced resistance to dislocation motion caused by coherency loss and coarsening of precipitates. Furthermore, theoretical and experimental analyses revealed an inverse relationship between the fatigue strength and the precipitate size (<i>Δσ</i>_-1p ∝ r^-1). These findings enable more reliable fatigue property predictions of precipitate-strengthened aluminum alloys under thermal service conditions.</p> Graphical abstract <p></p>