[Objective] To establish an RP-HPLC method for determination of isofraxidin of Acanthopanax giraldii Harms and to compare the isofraxidin content of different medical parts, different producing areas and different collection time of A. giraldii Harms. [Method] The RP-HPLC analysis was carried out at 25 ℃ on a Kromasil C18 column. The mobile phase consisted of acetonitrile-methano1-0.1 % phosphoric acid (V/V/V, 20∶ 10∶ 70) and its flow rate was 1.0 ml/min. The detective wavelength was set to 343 nm. [Result] The calibration curve was linear within the concentration ranges of 0.60×10-3 to 7.49 μg/ml. The regression equation for isofraxidin was written as y=2.636×104x-1.051×103, (r=0.999 7). The average recovery was 99.15% with RSD of 0.95%. [Conclusion] This method was simple, accurate and replicate. And it can be adopted for the quality control of A. giraldii Harms. [Objective] To establish an RP-HPLC method for determination of isofraxidin of Acanthopanax giraldii Harms and to compare the isofraxidin content of different medical parts, different producing areas and different collection time of A. giraldii Harms. [Method] The RP-HPLC analysis The mobile phase consisted of acetonitrile-methano 1-0.1% phosphoric acid (V / V / V, 20:10 70) and its flow rate was 1.0 ml / min. The detective was carried out at 25 ° C on a Kromasil C18 column The regression equation for isofraxidin was written as y = 2.636x104x-1.051x103, ((1) the calibration curve was linear within the concentration ranges of 0.60x10-3 to 7.49 μg / r = 0.999 7). The average recovery was 99.15% with RSD of 0.95%. [Conclusion] This method was simple, accurate and replicate. And it can be adopted for the quality control of A. giraldii Harms.