Abstract: The aim of the present study was to develop and optimize the extraction technology of total flavonoids from Polygonum hydropiper. Using total flavonoids content as an evaluation index, the extraction efficiency of six different methods were assessed and compared to screen the optimum extraction method; orthogonal design was employed to optimize the key parameters of ethanol final concentration in ethanol precipitation, ratio of solid to liquid and ultrasonic temperature in the screened optimum extraction method. The results showed that the highest yield （3.8%） of total flavonoids was obtained in enzymolysis-uhrasonic coupling method; the optimum extraction conditions were： ethanol concentration 60%, ratio of solid to liquid 1：30, ultrasonic temperature 60 ℃. The developed method has the advantages of simple operation, high reproducibility, low energy consumption, high efficiency, solvent saving and low cost; therefore, it can he used for the extraction of the total flavonoids in Polygonum hydrop ip e rum.