Objective:To analyze the chemical constituents of Rhizoma belamcandae by using high-performance liquid chromatography-diode array detector/electrospray ionization-mass spectrometry (HPLC-DAD/ESI-MS).Methods: Dried Belamcanda chinensis powder was extracted with 70% ethanol by sonication.The chromatographic separation was performed on a YMC ODS-C18 column (250 mm×4.6 mm I.D.,5 μm) with a mobile phase composed of 20%CH3OH(A)-70%ACN(B) (0→30→45→65 min,20→30→90→100 B),eluted at a flow rate of 0.45 ml/min,and the UV detection wavelength was set at 265 nm.Positive ionization mode with a needle voltage of 5 000 V,a capillary voltage of 20 V,a gas(N2)press of 20 psi and a temperature of the drying gas of 300℃ was selected.Relative molecular mass data acquisition was performed from m/z 250 to 550 in full MS scan mode.Results: Nine major isoflavones were identified from Rhizoma belamcandae based on their retention behavior obtained on-line by their UV spectra and the HPLC-DAD/ESI-MS.Conclusion: A rapid and efficient HPLC-DAD/ESI-MS method for identifying the chemical constituents of Belamcandae chinensis has been established,which provides more scientific information for quality control of Rhizoma belamcandae．