To investigate the stability of and in total flavonoids of Nymphaea candida in different physiologica pH and different biological media.A high performance liquid chromatographic method was established for the determination of nicotiflorin and astragalin in total flavonoids of N. candida,respectively,and the total flavonoids of N. candida was incubated in different phosphate buffer solutions with pH of 1.30-10.12,artificial gastrointestinal juice and isolated biological media.The concentration of the two were determined by HPLC and the residual percentages were calculated.The results showed that the stability of nicotiflorin and astragalin in acid-base solution was good.The two compounds were stable in artificial gastric juice,and poorly stable in artificial intestinal juice.The two compounds were stable in the contents of stomach and small intestine,but poor in the contents of large intestine.The stability of nicotiflorin and astragalin was more stable in the intestinal contents of rats after sterilization than before sterilization.Under the above conditions,nicotiflorin was more stable compared with astragalin from the total flavonoids of N. candida,which can provides a reference further research on the absorption and metabolism of total flavonoids of N. candida and the design of dosage forms after drug preparation.