Abstract: With dried powder of Eleocharis tuberosa peel as raw material and ethanol solution as solvent,flavonoids in Eleocharis tuberosa peel was extracted with decompressing inner ebullition method. The extraction technological conditions were optimized by single-factors experiments and response surface experiment. The results showed that the optimal extraction conditions was liquid-solid ratio of 35:1 mL/g,ethanol concentration of 50%,temperature of 70 ℃ and time of 30 min. Under the optimal conditions,the yield of flavonoids in five parallel experiments was 1.996%±0.010%,and the relative error was 0.25% compared with the theoretical prediction value of 2.001%. The influence order of the three factors on extraction effect of flavonoids in Eleocharis tuberosa peel was temperature > time > ethanol concentration. The theoretical basis was provided for the development and application of flavonoids in Eleocharis tuberosa peel by the result.