Objective To explore the impact of five-flavor Sophora flavescens enteric-coated capsules(FSEC)on the in-testinal flora of rats with ulcerative colitis(UC),so as to provide the reference for the mechanism of FSEC in treating UC.Methods Forty SPF-grade Wistar rats were randomly divided into the control group,the model group,the mesala-zine group and the FSEC group.Except the control group(0.9%sodium chloride solution),the other 3 groups used 3%dextran sulfate sodium(DSS)for 7 days to establish UC model.After successful modeling,the control group and the model group were given 2 mL/kgbw of 0.9%sodium chloride solution by gavage for 2 weeks,while the mesalazine group and the FSEC group were given 2 mL/kgbw of mesalazine suspension(0.2 g/kg)and FSEC granule suspension(2.16 g/kg),respectively.Pathological changes of colon tissue were observed after hematoxylin-eosin(HE)staining.Rat fecal samples were collected,and 16S rDNA high-throughput sequencing and bioinformatics analysis were performed on intestinal flora.The α and β diversity of intestinal flora among the four groups were compared,and the dominant flora was screened using LEfSe analysis.Results Compared with the control group,the model group showed a significant loss of colonic crypts and a large infiltration of inflammatory cells.Compared with the model group,the mesalazine group and the FSEC group exhibited a slight loss of colonic crypts,a small amount or an absence inflammatory cell in-filtration,and improved tissue damage.The α-diversity analysis showed that compared with the control group,the Chao1 and Shannon indices in the model group increased,while the Simpson index decreased;compared with the mod-el group,the Chao1 and Shannon indices in the mesalazine group and the FSEC group decreased,and the Simpson in-dex increased(all P<0.05).The β-diversity analysis showed that the sample distance between the FSEC group and the control group were more closer than that between the model group and the control group.LEfSe analysis results showed that the dominant bacteria in the model group were mainly from the Alistipes and Oscillospira.In the FSEC group,the dominant bacteria were from the Ruminococcus and Prevotella.Conclusion FSEC can improve the structures of intestinal flora,increase the abundance of beneficial bacteria such as Ruminococcus and Prevotella,reduce the abun-dance of pathogenic bacteria such as Alistipes,and alleviate the inflammatory response in UC rats.