Abstract: A RP-HPLC method for quantitative determination of oleanolic acid and ursolic acid in Rhododendron simsii Planch leaves was established. Kromasil C18 column(4.6 mm×250 mm,5 μm) was used as the chromatographic column,and methanol-0.2% aqueous solution of phosphoric acid(87:13) was used as the mobile phase running with a flow rate of 1.0 ml/min. The detection wavelength was 210 nm and the temperature of the column was 28 ℃. The linear rangers for oleanolic acid and ursolic acid are 0.458～9.16 μg(r=0.9996) and 0.516～10.32μg(r=0.9995),respectively. The average recoveries of the procedure are 99.45% for oleanolic acid and 98.49% for ursolic acid. Oleanolic acid is discovered for the first time in Rhododendron simsii Planch leaves. The determination results of the three batches of samples showed that the method is easy and accurate,which can be used for determination of oleanolic acid and ursolic acid in Rhododendron simsii Planch leaves.

Key words: Rhododendron simsii Planch leaves, RP-HPLC, oleanolic acid, ursolic acid, photodiode array detector