Objective: To identify the chemical constituents of Kuntai capsule by high performance liquid chromatography with electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). Method: The chemical components were analyzed and identified by using LC-ESI-MS/MS. The liquid chromatography separation was carried out on C18 column (4.6 mm×150 mm

5 μm) with acetonitrile-0.1% formic acid solution as the mobile phase for gradient elution. The flow rate was 1.0 mL·min-1 and column temperature was 30℃. The mass spectra were obtained in positive ion mode with electrospray ionization. The mass range recorder was set between m/z 50-1 500.The molecular weight was determined according to the molecular ion peaks. The compound structures were elucidated by comparing the data with literature data

including main ion peaks

UV spectrum and HPLC retention time information. Result: The 21 compounds were identified from Kuntai capsule

mainly including flavones and alkaloids. The flavones

such as baicalin

wogonoside

baicalein and wogonin

were identified from Scutellaria baicalensis. The alkaloids

such as palmatine

berberine

coptisine

jatrorrhizine

columbarine and magnoflorine

were identified from Coptis chinensis; paeoniflorin came from Paeonia lactiflora. Conclusion: The method is simple and rapid for identifying the main constituents of Kuntai capsule. This paper has laid a foundation for further studying and testing the quality of Kuntai capsule.