Abstract:In order to optimize the extraction process of total flavonoids in sweet tea，the extraction process of cellulase ethanol extraction，ethanol hot reflux extraction and ultrasonic ethanol extraction was optimized.The experiment was carried out by the combination of single factor and uniform design method.The extraction rate of total flavonoids in sweet tea was taken as the index，and the experimental data of uniform design were regressed analysis and two polynomial stepwise regression analysis.The experimental results showed that the optimum technological conditions for the extraction of cellulase and ethanol were enzyme addition was 4.3 mg（0.86%），the pH value of the hydrolysate was 5.4，the hydrolysis temperature was 42℃，and the enzymolysis time was 65 min，under this conditions the maximum extraction yield of the total flavonoids was 10.89%.The optimum technological conditions for the ethanol reflux extraction were ethanol concentration was 63%，the ratio of the material to liquid was 1 ∶58（g/mL），the extraction temperature was 60 ℃ and the extraction time was 120 min，underthisconditionsthemaximumextractionyieldofthetotalflavonoidswas11.53%.The optimum technological conditions for the ultrasonic ethanol extraction were as follows：the ethanol concentration was 68.9%，the ratio of the material to liquid was 1∶30（g/mL），the ultrasonic power was 73.9 W，the extraction temperature was 62.2℃，and the extraction time was 67.7 min，under this conditions the best extraction rate of flavonoids from sweet tea was 12.23%.Compared with the three extraction methods，the average extraction yield of ultrasonic ethanol extraction method was 12.23%＞the average extraction yield of ethanol hot reflux extraction was 11.53% ＞the average extraction yield of cellulase ethanol extraction was 10.89%，the difference between the three extraction methods on the yield of total flavonoids of sweet tea reached a high（very）significant level.