[Objective] To optimize the extraction process of flavonoids from HERBA PHYLLANTHI URINARIAE by response surface methodology.[Method] Using extraction temperature,extraction time and solid-liquid ratio as independent variables and the yield of flavonoids as response value,response surface methodology with three-factors and three-levels was carried out for optimizing the extraction process of flavonoids from HERBA PHYLLANTHI URINARIAE on the basis of Box-Benhnken central composite design principles.[Result] The optimum extraction conditions of flavonoids were as follows:solid-liquid ratio of 1:18,extraction temperature of 66 ℃ and extraction time of 140 min.Under this condition,the yield of flavonoids was up to 2.43%.[Conclusion] This study could provide a theoretic basis and reference datum for extensive industrialization of HERBA PHYLLANTHI URINARIAE. [Objective] To optimize the extraction process of flavonoids from response surface methodology. [Method] Using extraction temperature, extraction time and solid-liquid ratio as independent variables and the yield of flavonoids as response value, response surface methodology with three -factors and three-levels was carried out for optimizing the extraction process of flavonoids from HERBA PHYLLANTHI URINARIAE on the basis of Box-Benhnken central composite design principles. [Result] The optimum extraction conditions of flavonoids were as follows: solid-liquid ratio of 1: 18, extraction temperature of 66 ° C and extraction time of 140 min. Under this condition, the yield of flavonoids was up to 2.43%. [Conclusion] This study could provide a theoretic basis and reference datum for extensive industrialization of HERBA PHYLLANTHI URINARIAE .