OBJECTIVE To investigate the multiple bioactive constituents in Gegen Qinlian decoction and evaluate its bioactivity and quality control. METHODS A high performance liquid chromatography with diode array detection (HPLC-DAD) method for the simultaneous qualitative determination of multiple components was developed. The separation was performed on a Kromasil C18 column by gradient elution with acetonitrile and ammonium acetate (containing 0.3% triethylamine, and adjusted pH 4. 3 using 1% glacial acetic acid) as the mobile phase at a flow-rate of 0.7 mL/min, the column temperature was maintained at 30 degrees C, HPLC chromatographic comparison between Gegen Qinlian decoction, four medicinal material and 14 components were carried out to investigate components in the composite formula. RESULTS 23 characteristic peaks were identified and could be dated back to four medicinal materials from Gegen Qinlian decoction, in which 12 peaks were identifed by standards. CONCLUSION This readily available, low-cost and reliable HPLC-DAD method can be used for simultaneous analysis of multiple bioactive constituents of Gegen Qinlian decoction and will improve the quality control of Gegen Qinlian decoction.