Abstract: A method was developed to analyze and identify the chemical constituents of Swertia chirayita by ultra-performance liquid chromatography-electrospray ionization quadrupole time-of-flight mass spectrometry (UPLC-ESI-Q-TOF MS). After extracted by methanol, the sample was separated on an Acquity HSS T3 reverse phase column (2.1 mm×100 mm, 1.8 μm) with the gradient elution of 0.1% formic acid in ACN and 0.1% formic acid in water as mobile phases, and the flow rate was 0.4 mL/min. The electrospray ionization (ESI) source in positive or negative ion mode was used for multiple reaction monitoring (MRM) mode. The results indicated that 24 compounds from the ethanol extract of Swertia chirayita are identified, including six iridoids, eleven xanthones, two flavonoids, two isocoumarins, two phenols and one terpenoid, by direct comparison with both positive and negative ion mass data, the element compositions analysis, the data base of Scifinder, standards and literatures. Six of these compounds are found from this specie for the first time, including loganic acid, isomangiferin, erythrocentauric acid, amaroswerin, 3-O-demethylswertipunicoside and iriflophenone. This method is rapid, simple, sensitive, which can provide the reference for evaluation of the quality of the Swertia chirayita and clarifying the material basis.