<p>As a plasma-facing material (PFM), tungsten is subjected to the synergistic irradiation of steady-state plasma and transient thermal load. The study investigated the irradiation damage and subsequent performance degradation of tungsten (W) at different preheating temperatures under synergistic irradiation of 180 MW·m⁻². The findings revealed that increasing the preheating temperature resulted in the fusion of smaller grains into larger ones, a decrease in dislocation line density, and a reduction in reflection. When the preheating temperature was below the ductile-to-brittle transition temperature (DBTT, ~ 400 °C), defects trapped hydrogen and formed a bubble-like structure on the surface with crack widths ranging from 100 to 300 nm. The pinning effect of hydrogen retention caused an increase in hardness, but as the pinning effect weakened, large cracks led to a decrease in hardness. Preheating W above the DBTT resulted in no bubble-like structures on the surface and reduced crack widths to below 100 nm, with a corresponding increase in hardness, indicating reduced damage. Therefore, when tungsten is used as a PFM in nuclear fusion reactions, its preheating temperature should be controlled above the DBTT to ensure it remains in a ductile state with strong irradiation resistance.</p> Graphical abstract <p></p>