Turkish galls have been reported to exhibit remedial effects in ulcerative colitis (UC). However, the active constituents of Turkish galls for the treatment of UC remain unclear. The objective of this study was to screen for anti-inflammatory active constituents and clarify their associated molecular mechanisms. Therefore, systems pharmacology was developed to predict the relationship between constituents and the corresponding targets as well as pathways. In addition, mass spectrometry-guided preparative chromatography technique was used for preparing constituents to evaluate the anti-inflammatory activities and the therapeutic efficacy against UC. In silico, active constituents exhibited a remedial effect on UC possibly by regulating multiple pathways and attacking multiple targets, of which those involved mainly in the NF-κB pathway were selected for verification. In vitro, 5 categories of constituents were screened as active constituents by comparing the cytotoxicity and detecting the level of the pro-inflammatory factors of 9 category constituents. In vivo, dextran sulfate sodium (DSS)-induced UC was significantly ameliorated in active constituents-fed mice. The results indicated that the active fraction comprising methyl gallate, digallic acid, di-O-galloyl-β-d-glucose, and tri-O-galloyl-β-d-glucose primarily contributed to the treatment of UC. Moreover, active fraction could also inhibit the phosphorylation level of IKKβ, thus inhibiting the downstream NF-κB signaling pathway. The approach developed in this study not only clarifies the anti-inflammation effect of Turkish galls but also provides a beneficial reference for the discovery of the base material and functional mechanism of this herbal medicine.