Abstract: A method of ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF MS) was established to analyze the chemicals in Euodia rutaecarpa hepatotoxic part and metabolic components in rat blood. Under the optimized condition of chromatography and mass spectrometry, the data collection for the compounds in the mass range of m/z 50-1200 was performed using positive ion scanning mode within 12 min. The collected data were analyzed based on UNIFI software combined with artificial analysis. According to the precise mass information of precursor ions and fragment ions offered by high resolution mass spectrometry, the molecule composition of compound was preliminarily speculated. Finally, a total of 29 constituents in hepatotoxic part are identified combined with substances and reference data, including 9 indole alkaloids, 10 quinolone alkaloids, 5 triterpenoids, 3 flavonoids, one other alkaloid and one organic acid. 21 compounds in blood are characterized, including 15 prototypes and 6 metabolites (a compound unknown) by comparing the base peak ion chromatograms of samples in vivo and in vitro combined with MS data, compound fragmentation laws and published literatures. The metabolic pathways of metabolites were further speculated. This method can provide, a reliable data support to indicate hepatotoxic components of Euodia rutaecarpa.