Objective: To identify the compounds in herb of Eucommia ulmoides by ultra-performance liquid chromatography PDA electrospray ionization tandem mass spectrometry (UPLC-PDA-ESI-MS). Method: The chromatographic separation was carried out at 45 ℃ on a BEH C18 column (2.1 mm×100 mm

1.7 μm) eluted in the gradient program. The mobile phase consisted of acetonitrile and water (both containing 0.1% formic acid). The detecion of PDA was set between 190 nm and 400 nm. The mass spectra were obtained by Waters ACQUITYTM triple quadrupole tandem mass spectrometer in negative ion mode with ion spray voltage 3 kV. The temperature of the source and desolvation was set at 120 ℃ and 350 ℃ separately. Nitrogen was used as the desolvation gas (650 L·h-1) and cone gas (50 L·h-1). For collision induced dissociation

argon was used as the collision gas at a flow rate of 0.16 mL·min-1. The mass range recorder was set between 100-1 000 m/z. Result: Three lignin

four iridoid and four phenyl propanoid were well separated and identified by the method. Conclusion: The method is simple and rapid for the identification and quality control for the herb of E. ulmoides.