【Objective】Rubus idaeus (red raspberry) fruits are renowned for their rich nutritional profile, particularly their high content of natural antioxidant compounds such as total phenols, flavonoids, and vitamin C (VC). To optimize the development and utilization of this valuable resource, this study aims to systematically investigate the appearance quality, dynamic changes in antioxidant content, and expression patterns of antioxidant enzyme-related genes of red raspberry at different developmental stages.【Method】The study employed the superior red raspberry cultivar ‘Autumn Bliss' as the experimental material. A comprehensive analysis was conducted to measure the fruit's appearance, quality, antioxidant indicators and antioxidant enzyme activity at different developmental stages. Methods such as anthrone colorimetry, sodium hydroxide titration, hydroxylamine method and quantitative real-time PCR (qRT-PCR) were utilized. The expression characteristics of antioxidant enzyme genes were analyzed, and the correlation and principal component analysis were performed to elucidate the relationships among the measured indicators.【Result】The fresh weight and transverse and longitudinal diameter of red raspberry fruit gradually increased with fruit maturity, while the fruit luminosity gradually decreased, and the trend of chroma change was initially increasing and then decreasing. As the red raspberry fruit gradually matures, the sugar acid ratio showed a gradually increasing trend, reaching its highest value of 5.91 at 35 days after flowering (DAF). The contents of total phenol, flavonoid and VC content showed an overall downward trend during the development of red raspberry fruits, with the highest content during the green fruit stage and a positive correlation with total antioxidant capacity. The content of anthocyanins showed an upward trend and reached its highest point during the mature stage, with a mass fraction of 802.42 μg/g. In terms of antioxidant enzyme activity, the POD activity (62.58 U/g) and glutathione (GSH) mass fraction (1.01 mg/g) were highest during the green fruit stage, respectively, showing an extremely significant positive correlation with the total antioxidant capacity. In contrast, SOD activity, MDA content, and {\mathrm{O}}_2^{-} production rate were highest at maturity and negatively correlated with total antioxidant capacity. The expression levels of SOD activity related genes RuSOD1 and RuSOD2 showed overall upward trends during fruit development, while the expression levels of RuSODCP.2 also showed an upward trend in the early stage and slightly decreased in the mature stage. The overall change in the expression level of RuFSD was not significant. And they were positively correlated with SOD activity. The expression level of the genes related to POD activity, RuPOD, gradually decreased. The expression level of RuPER5 decreased during the 7-14 DAF period and increased during the 14-35 DAF period, while the expression level of RuPER25 increased during the 7-21 DAF period and decreased during the 21-35 DAF period. The expression level of RuPROX6 gradually increased, while the expression level of RuPER17 did not change significantly. POD activity was positively correlated with the expression levels of RuPOD, RuPER5, RuPER17 and RuPER25, while it was negatively correlated with RuPROX6.【Conclusion】The findings indicate that red raspberry fruits exhibit the highest antioxidant capacity during the green fruit stage, with total phenols, flavonoids, POD and GSH identified as the primary antioxidant components. This research provides a foundation for further exploration into the dynamics changes and action mechanisms of antioxidant substances in red raspberry fruits, offering valuable insights for their potential applications in nutrition and health.