Abstract: A comprehensive analytical method based on UPLC-QTRAP-MS/MS was developed for the simultaneous determination of eighteen bioactive components including phenolic acids, anthraquinones and flavonoids in Xanthii Herba and Xanthii Fructus. Under the optimized chromatographic conditions, extracts of eighteen target components were obtained on an Agilent ZORBAX SB-C18 column (250 mm×4.6 mm×5 μm) using methanol-0.2% formic acid as mobile phases for gradient elution. The flow rate was 1.0 mL/min and the column temperature was 35 ℃. The target compounds were analyzed in the negative ion multiple reaction monitoring (MRM) mode. The results show that eighteen components have good linearity, the correlation coefficients of all the calibration curves are higher than 0.999 4. Relative standard deviations （RSDs） of precision, repeatability and stability are lower than 3%. The recoveries range from 96.81% to 102.78%, and the RSDs are less than 3%. The established method is accurate, sensitive, and has good repeatability. It is suitable for simultaneous determination of eighteen components in Xanthii Herba and Xanthii Fructus, which can provide a reliable and effective technique for the quality control of Xanthii Herba and Xanthii Fructus.