Abstract: Mung bean soup (MBS), as a traditional Chinese beverage renowned for its efficacy in "clearing summer heat," is rich in phenolic compounds and possesses significant antioxidant and anti-inflammatory activities. However, it is highly susceptible to reddening. Currently, the changes in bioactive components, functional activities, and sensory qualities associated with the reddening of MBS remain insufficiently understood. Therefore, this study systematically investigated the variations in chromaticity, acidity, phenolic composition and content, antioxidant capacity, anti-inflammatory activity, and sensory quality of MBS following reddening under three different storage temperatures（4 °C, 20 °C, and 37 °C）.The results indicated that elevated storage temperatures accelerated the reddening process of MBS and exerted a more significant impact on its functional activities and sensory quality. Compared with fresh MBS, samples stored at all temperatures exhibited reddening. The group stored at 37 °C showed the most distinct changes, with the redness value (a^*) increasing by 110.05% and the lightness value (L^*) decreasing by 19.60% when compared with the fresh group. Most of bioactive components decreased significantly as the reddening intensified. Under 37 °C storage, the contents of total phenolics, total flavonoids, and condensed tannins decreased by 18.27%, 16.77%, and 59.36%, respectively. Furthermore, the retention rates of key bioactive components, vitexin and isovitexin, were only 40.39% and 35.69%, respectively. Consequently, the FRAP antioxidant capacity and trypsin inhibitor activity decreased by up to 42.78% and 27.78%, respectively. The results of sensory evaluation further demonstrated that the occurrence of reddening significantly influenced the color, aroma, taste, and mouthfeel of MBS. These findings provided a fundamental scientific basis for the precision processing and nutrient preservation of traditional summer beverages, contributing to the high-quality production of MBS.