Abstract: The aim of this paper was to explore the process of β-glucosidase-assisted extraction of flavonoids from thinned fruits of Guanxi pummelo and the inhibitory effect of the extracted flavonoids on tyrosinase. In this paper, the extraction amount of total flavonoids was used as the index, and the β-glucosidase activity, enzymatic hydrolysis pH, temperature and time were optimized by single factor and response surface experiments, and the inhibitory effect of total flavonoids extract on tyrosinase was studied. The results showed that the optimal conditions for the extraction of flavonoids from thinned fruits of Guanxi pummelo were as follows: β-Glucosidase enzyme activity 0.0128 U/mL, enzymolysis pH4.4, temperature 35 ℃, time 4.8 h. Under these conditions, the extraction amount of total flavonoids was 34.0 mg/g, the half maximal inhibitory concentration (IC₅₀) of the flavonoids extract on tyrosinase was 0.31 mg/mL. The results of this study showed that the enzymatic process could significantly improve the extraction amount of flavonoids from thinned fruits of Guanxi pummelo, and the flavonoids from thinned fruits of Guanxi pummelo had strong tyrosinase inhibition. The results of this study provided a reference for the extraction and application of flavonoids from thinned fruits of Guanxi pummelo, which was conducive to promoting the high-value utilization of Guanxi pummelo.