The flavonoids content in the preparartion of Folium Ginkgo was determined by reserved HPLC on ODS column,using 0. 4% phosphoric acid-methanol (1:1) as mobile phase,detection wavelength at 360nm. The sample was extracted by the method of methanol and ultrasonic wave,and hydrolyzed with 4% sulfuric acid. After being limited in accurate volume and filtrated,it was determined by the external standard method. Using quercitin as a control, there are a linear range of 0. 5~2. 5mg/ml,and a correlation coefficient(...