To determine carboxyatractyloside and atractyloside in Xanthii Fructus by HPLC.By HPLC, Agilent ZORBAX SB-phenyl (4.6 mm x 250 mm, 5 microm) column was adopted, with acetonitrile-0.01 mol x L(-1) NaH2PO4 (pH 6) as the mobile phase for gradient elution at the flow rate of 1.0 mL x min(-1). The detection wavelength was 203 nm, and the temperature was set at 35 degrees C.Carboxyatractyloside showed a good linearity within the range of 0.0972-1.944 microg and atractyloside showed a good linearity within the range of 0.1030-2.060 microg. The recovery rate of carboxyatractyloside was 100. 3% and that of atractyloside was 102.5%. The RSD were 0.67% and 1.4% (n=6).This method is so simple, practical and highly repeatable that is can be used for quality control of Xanthii Fructus.