[Objective] To investigate the changes in chem. constituents of Radix Bupleuri before and after processing.[Methods] The chem. constituents of Radix Bupleuri were detected before and after processing with UV, HPLC and TLC methods.[Results] The chromatog. conditions were determined as follows: chromatog. column of Kromasil C18(4.6 mm × 250 mm, 5 μm), column temperature of 25 °C, mobile phase of acetonitrile (A) -water (B), gradient dilution of phase A at 10% within 0 - 3 min, phase A at 10% - 15% within 3 -5 min, phase A at 15% - 25% within 5 -20 min, phase A at 25% - 40% within 20 -30 min, phase A at 40% - 55% within 30 -40 min, phase A at 55% - 75% within 40 - 45 min, phase A 75% - 90% within 45 - 60 min.Under these parameters, the chem. constituents could be well separatedComparison of HPLC fingerprints showed that chem. constituents in raw and processed Radix Bupleuri were changed remarkably, and some new constituents produced after processing.Thin layer chromatog. conditions were determined as follows: expansion system of chloroform - methanol - water (100:20:1, V/V/V), chromogenic agent of 5% vanillin-sulfuric acid to heat to 105 °C till the appearance of clear spots.The spot location of TLC fingerprints of chem. constituents differed between raw and processed Radix Bupleuri.[Conclusion] UV, HPLC and TLC all confirmed the changes of chem. constituents of Radix Bupleuri before and after processing.