In order to explore the chemical constituents of Foeniculum vulgare Mill.cortex in the treatment of liver fibrosis,and to reveal its pharmacodynamic material basis and mechanism of action.In this study,UPLC-Orbitrap-MS/MS technology was used to qualitatively identify the chemical constituents of the ethanol extract,petroleum ether fraction,ethyl acetate frac-tion,n-butanol fraction and water fraction of the F.vulgare cortex.According to the mass spectrometry fragmentation rule,ref-erence substance verification and literature search,58 common compounds of each component were speculated and identified.MTT assay was used to detect the effect of each component on the proliferation of HSC-T6 cells,and the potential active com-pounds against liver fibrosis were screened by spectrum-effect relationship.The results of spectrum-effect relationship showed that dihydrocapsaicin,harmine and isoscopoletin contributed more to the anti-hepatic fibrosis of F.vulgare cortex.The anti-he-patic fibrosis activity and mechanism of monomeric compounds were verified in vitro.The results showed that dihydrocapsai-cin,harmine and isoscopoletin had a good inhibitory effect on activated HSC-T6(P<0.01,0.001),and could inhibit the ex-pression of α-SMA(P<0.01,0.001).Dihydrocapsaicin and harmine had strong pro-apoptotic effects and could down-regu-late the relative expression of Bax/Bcl-2 and Caspase3(P<0.05,0.01).It is indicated that the pharmacodynamic sub-stances of F.vulgare cortex against liver fibrosis may be dihydrocapsaicin,harmine,isoscopoletin,scopoletin,7-hydroxycouma-rin,etc.The mechanism may be to inhibit the activation of hepatic stellate cells and regulate the expression of Bax/Bcl-2,which reflects the multi-component and multi-target anti-liver fibrosis characteristics of F.vulgare cortex.