Abstract: OBJECTIVE To qualitative analysis of the chemical constituents of Cayratia japonica and establish a quantitative analysis method for the main components. METHODS ACQUITY UPLC HSS T₃ chromatographic columns (2.1 mm×50 mm， 1.8 μm) were selected， acetonitrile (B)-0.1% formic acid aqueous solution (A) was used as mobile phase for gradient elution， a flow rate of 0.4 mL/min， mass spectrometry using electrospray (ESI) ion source to collect data in positive and negative ion mode.The results were analyzed by PeakView software. Then according to the relative retention time， excimer ion peak and fragment ion peak of the compound， the chemical composition was analyzed according to the reference material and related literature. The quantitative analysis of four main components (luteolin-7-O-glucoside， apigenin-7-O-glucoside， luteolin， apigenin) were established. RESULTS A total of 31 chemical constituents were identified in Cayratia japonica， including 7 flavonoids and their glycosides， 3 coumarins， 7 terpenoids and triterpenoids， 7 fatty acid esters and 8 other classes. The contents of luteolin-7-O-glucoside， apigenin-7-O-glucoside， luteolin and apigenin in three batches of Cayratia japonica were 0.061%~0.15%， 0.077%~0.14%， 0.011%~0.028% and 0.020%~0.062%， respectively. CONCLUSION This method can analyze quickly and accurately the constituents of Cayratia japonica and the quantitative analysis method could be used for quality control of Cayratia japonica.