Objective:To establish an HPLC method by gradient elution for comparative analysis of the ef-fective composition in two kinds of Yinhuang decoction.Method:The column was Diamonsil C18（4.6 mm × 250 mm

5 μm）.The mobile phase was consisted of acetonitrile-0.1% phosphoric acid with gradient elution.The flow rate was 1.0 mL·min-1 and the detection wavelength were at 276 nm and 328 nm for the content determination of chlorogenic acid

baicalin and wogonoside.Results:Chlorogenic acid

baicalin and wogonoside were linear in the range of 0.011 8-0.059 μg（r = 0.999 9）

0.19-9.5 μg（r = 0.999 9） and 0.0104-0.52 μg（r = 0.999 9） respec-tively.The average recoveries of them were 98.30%

102.87% and 104.33% respectively.The total solid content of Yinhuang decoction separated by filtration membrane was more than 50% compared with that of Yinhuang oral liq-uid（13.36%）.Conclusion:The HPLC can be applied to content determination of chlorogenic acid

baicalin and wogonoside in Yinhuang decoction

the content of effective parts separated by filtration membrane was more than 50%.Filtration membrane was conducive to developing the fifth class new drugs.