BACKGROUND The aim of this study was to determine the effect of kangfuxin liquid (KFXL) on inflammatory response, and its underlying mechanism in treating acute ulcerative colitis (UC) in mice induced by dextran sulfate sodium (DSS). MATERIAL AND METHODS Mice were provided drinking water containing DSS (3%) for 7 days to induce acute enteritis. The mice were divided into 6 groups: a control group, a DSS-induced (vehicle) group, a sulfasalazine (SASP) group, and low-, medium-, and high-dose kangfuxin liquid groups. Disease activity index (DAI), colon mucosa damage index (CMDI), histopathological score (HS), and organ index were monitored daily. The levels of interleukin-1ß (IL-1ß), interleukin-10 (IL-10) in serum and interleukin-17 (IL-17) and epidermal growth factor (EGF) in colon tissue were assessed by enzyme-linked immunosorbent assay (ELISA). Flow cytometry was used to assess the changes of T lymphocyte subsets in spleens of mice to evaluate the therapeutic effect of drugs on acute UC in mice. RESULTS Different doses of kangfuxin liquid reduced the DAI, CMDI, and HS scores (P<0.01 or P<0.05) of acute UC mice, reduced the level of IL-1ß and IL-17 in serum, increased the expression of IL-10 in serum and EGF in colon tissue, increased the number of CD3⁺ T cells, and decreased the level of CD4⁺ T cells and the ratio of CD4⁺/CD8⁺. CONCLUSIONS Kangfuxin liquid has a therapeutic effect on DSS-induced acute UC in mice, and its mechanism of action may be associated with regulating immune function and reducing intestinal inflammatory response.