ObjectiveTo explore the potential mechanism of different processed products of Baiyaojian and its compound Xiangmei pills in rats with ulcerative colitis（UC） by comparing the pharmacodynamic and metabolomic differences. MethodEighty SD rats were acclimatized and kept for 3 d， and randomly divided into 8 groups［blank group， model group， mesalazine group（0.4 g·kg^-1）， Baiyaojian group（1.89 g·kg^-1）， stir-fried Baiyaojian group（1.89 g·kg^-1）， carbonized Baiyaojian group（1.89 g·kg^-1）， and Xiangmei pills low and high dose groups（1.89， 5.67 g·kg^-1）］， with 10 rats in each group. Rats in the blank group were administered physiological saline by gavage， and rats in the remaining 7 groups were orally administered 5% dextran sodium sulfate（DSS） solution daily for 8 consecutive days to induce UC model. After successful modeling， each dosing group was given the corresponding dose of drug solution by gavage， and the blank and model groups were given equal amounts of saline by gavage， and the drug was administered continuously for 8 d. Then serum levels of tumor necrosis factor-α（TNF-α）， interleukin（IL）-6， IL-10 and IL-1β were measured by enzyme-linked immunosorbent assay（ELISA）， hematoxylin-eosin（HE） staining was used to observe the histopathological changes of colon tissue， the proportion of T helper 17 cells（Th17） and regulatory T cells（Treg） in the peripheral blood of rats in each group was detected by flow cytometry. The endogenous metabolites in serum of rats were detected by ultra performance liquid chromatography-quadrupole/electrostatic field orbitrap high-resolution mass spectrometry（UPLC-Q-Exactive Orbitrap MS）， and the differential metabolites were characterized by combining principal component analysis（PCA） and orthogonal partial least squares-discriminant analysis（OPLS-DA）， and were analyzed according to the variable importance in the projection（VIP） value>1.0 and P<0.05， and potential metabolic pathways were analyzed according to Human Metabolome Database（HMDB）. ResultCompared with the blank group， the colon tissue of the model group was congested and the mucosa was ulcerated， the colon length was significantly reduced（P<0.01） and the quality was significantly increased（P<0.05）， the proportion of Th17/Treg in the peripheral blood and the serum levels of TNF-α， IL-6 and IL-1β were significantly increased， while the IL-10 expression wassignificantly reduced（P<0.05， P<0.01）. Compared with the model group， the colon tissue of UC rats in each treatment group was improved with scattered ulcers， reduced inflammatory cell infiltration， significantly increased colon length， and significantly decreased mass（P<0.05）， the proportion of Th17/Treg in the peripheral blood decreased， the expression of TNF-α，IL-6 and IL-1β was significantly reduced（P<0.05， P<0.01）， while the IL-10 expression was significantly increased（P<0.01）. The therapeutic effect of different administration groups on UC was in the order of high dose group of Xiangmei pills>low dose group of Xiangmei pills>carbonized Baiyaojian group>stir-fried Baiyaojian group>Baiyaojian group. And a total of 26 differential metabolites were screened in the metabolomics results. Compared with the blank group， 14 differential metabolites were up-regulated and 5 metabolites were down-regulated in the model group， and 14， 9， 14， 12 and 17 metabolites could be recalled in the Baiyaojian group， stir-fried Baiyaojian group， carbonized Baiyaojian group， Xiangmei pills low and high dose groups. The main metabolic pathways involved were citrate cycle pathway， pantothenic acid and coenzyme A biosynthesis pathway， aromatic hydrocarbon receptor（AhR） signaling pathway， glycolysis/gluconeogenesis pathway. ConclusionThe therapeutic effect of Baiyaojian on UC is significantly improved after charcoal stir-frying， and the efficacy is more prominent when combined with Angelicae Dahuricae Radix and Mume Fructus Carbonisata， which can provide a basis for the development of Baiyaojian compound preparations.