Objective: To analyze and evaluate the chemical constituents of Citrus reticulata ‘Shiyue Ju’ rapidly by using ultra-high performance liquid chromatography tandem quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) technique. Method: The LC separation was performed on a UPLC Aglient Zorbax Extend C18 column (4.6 mm×50 mm

1.8 μm)

with 0.1% formic acid solution (A)-acetonitrile solution (B) as the mobile phase for gradient elution. The flow rate was 0.6 mL·min-1; column temperature was set at 35 ℃; and injection volume was 0.5 μL. Electrospray ion (ESI) source was applied for the TOF-MS analysis under the positive ion mode; the mass scanning range was between m/z 100-1 000; and the running time was 24 min. By using target compound screening method in the mass spectrometry analysis software

the structures of monitored chemical compositions were identified and speculated by retention time

exact relative molecular weight and the secondary mass spectra fragment of MS. Result: Under certain chromatographic conditions

thirty-one chemical compounds were separated and identified completely from the methanol extraction of C. reticulata ‘Shiyue Ju’ based on reference substances and related references

including five flavone C-glycosides

six flavone O-glycosides

seventeen polymethoxylated flavonoids (PMFs)

alkaloid and two polyphenols compounds. Conclusion: The established detection method was convenient and accurate

providing an analytical approach for rapidly identifying and analyzing the chemical compounds. The study supplied the scientific basis to become available for the development and utilization of citrus resources.