Abstract:Using ethanol as extracting agent， the extraction technology of total flavonoids （TP） in astragalus stems with surfactants assisted with microwave method and antioxidant ability of TP extraction solution in vitro were studied. Applying extraction efficiency of TP to evaluation indicator， the extraction technology of TP in as－ tragalus stems was optimized on the base of the single factor experimental results. The antioxidant ability of TP extraction solution in vitro was evaluated according to its clearance ratio to both DPPH·and·OH free radical. The optimum extracting agent， ratio between material and solvent， the microwave power， the addition of CTAB （cetyl trimethyl ammonium bromide） surfactant， extracting temperature and extracting time were 45 % ethanol aqueous solution， 1 ∶ 17 （g/mL）， 600 W， 0.4 % dry weight of raw medicinal materials， 50 ℃ and 10 min re－ spectively. The extraction efficiency of TP could reach 37.62 mg/g under the optimum extracting condition， which increase extraction efficiency by 11.87 mg/g compared with single microwave extracting method. The ex－ perimental results had shown that extraction technology of TP with surfactants assisted with microwave method was high efficient and TP extraction solution had certain antioxidant ability in vitro.