OBJECTIVE:To establish the method for determination of baicalin in Chang’an capsule by RP-HPLC. METHODS:HPLC was performed on C 18 column with methanol-0.07%phosphoric acid solution(44∶56)as mobile phase at a flow rate of lml/min and the temperature of column kept at room temperature.The UV detection wavelength was280nm.RESULTS:The linear range of baicalin was sample size0.1054?g~1.0540?g(r=0.9996),the average recovery was97.44%(RSD=2.92%,n=5).CONCLUSION:The method was simple,accurate and fast,and can be used for the determination of baicalin.