Abstract: Flavonoids in peanut hull were extracted by the ball milling method. The effects of solid-liquid ratio, ball milling time, and ethanol volume fraction on the extraction yield of flavonoids were investigated by single factor experiments. The Box-Behnken response surface methodology was used to optimize the extraction process, and the scavenging rate of superoxide free radical was also studied. The results showed that the optimal extraction conditions were as follows: Solid-liquid ratio of 1:25 g/mL, ball milling time of 60 min, and ethanol concentration of 60%, and the extraction yield of flavonoids could reach (32.1±0.13) mg/g. The scavenging capacity of superoxide free radicals was 53.53% when the concentration of flavonoids was 0.012 mmol/L. This work proved that ball milling was an effective extraction method and would provide the theoretical data support for further research.