Abstract: With eleocharis tuberosa peel as raw materials, the flavonoids in eleocharis tuberosa peel was extracted with cellulase-assisted low eutectic solvent method, to improve the extraction effect. Single-factor experiments and response surface experiments were used to optimize the conditions, such as water content of the solvent, liquid-solid ratio, and enzyme dosage, and it were also compared with the extraction effect of no enzyme method and no low eutectic solvent method. Otherwise, the antioxidant activity was preliminarily investigated by determining the hydroxyl radical clearing rate of the flavonoid extract. The result showed that, for simple operation, the optimum extraction conditions gotten after optimizing, were water content of solvent of 30%, liquid-solid ratio of 35:1 mL/g, and enzyme dosage of 3%, in which conditions the theoretical prediction value of flavonoid yield was 2.0600%. The average flavonoid yield of eleocharis tuberosa peel, gotten by parallel experiments under the optimum conditions, was 2.0808%(the relative standard deviation, RSD＝0.55%), and the relative deviation to the theoretical prediction value of 2.0600% was 1.01%. By comparative experiments，it was known that, the average flavonoid yield was far higher than the yield gotten by no enzyme method and no low eutectic solvent method, which verified that synergetic effect between cellulase and the low eutectic solvent. By determining the hydroxyl radical clearing rate, it indicated that, the flavonoid gotten by the experimental method, had stronger antioxidant activity.