Abstract: To elucidate the differential mechanisms of oak barrel ageing on the quality of monovarietal and blended dry red wines, this study employed Syrah monovarietal wine and Syrah-Petit Verdot blend (90:10) wine as experimental materials. Both wines were aged for 12 months in Wolin oak barrels with stainless steel tanks serving as the control. The dynamic changes in basic physicochemical parameters and phenolic compounds were systematically analyzed, and the volatile aroma components were comprehensively evaluated using principal component analysis (PCA) and odor activity values (OAV). The results showed that the micro-oxidative environment of oak barrels significantly increased the contents of total phenols, tannins, and oak-derived aroma compounds in both wines (P<0.05). However, the evolution pathways of anthocyanins differed between the two wines. After 12 months of oak aging, the monovarietal wine exhibited a lower degradation rate of monomeric anthocyanins (35.84%) and a higher degree of methylation, presenting a bright purple-red color. In contrast, the blended wine underwent more extensive anthocyanin transformation (64.70% degradation), which promoted the formation of polymeric pigments and resulted in a shift toward a mature brick-red color. PCA and sensory evaluation further revealed that oak aging differentially reshaped the aroma profiles of the two wines. The monovarietal wine more effectively retained fruity esters and accumulated key oak-derived compounds such as vanillin and oak lactone, resulting in a complex aroma combining fresh fruit and woody notes. The blended wine, on the other hand, exhibited more pronounced smoky characteristics from volatile phenols and achieved the highest overall sensory score.