〔Abstract〕 To explore the alleviating effect of geniposide on ulcerative colitis (UC) and to investigate its potential mechanism . Methods A UC mouse model was induced using 5% dextran sulfate sodium ( DSS) . These mice were randomly divided into 6 groups ( n = 8) : control group , model group , sulfasalazine group[ 100 mg/(kg ·d) ] , low-dose geniposide group[ 10 mg/(kg ·d) ] , medium-dose geniposide group[20 mg/(kg ·d) ] , and high-dose geniposide group[40 mg/( kg · d) ] . The mice were orally administered for consecutive 10 days . The colon length and mouse body mass were measured , and the colon mucosal damage index (CMDI) and disease activity index (DAI) were scored . The pathological changes in colon tissue were observed using hematoxylin-eosin (HE) staining. The reagent kits were used to measure the levels of malondialdehyde ( MDA) , myeloperoxidase (MPO) , catalase ( CAT) , and glutathione ( GSH) in colon tissue . The enzyme linked immunosorbent assay (ELISA) was used to analyze the expression levels of tumor necrosis factor-α ( TNF-α) , interleukin-6 ( IL-6) , and IL-1βin colon tissue . Western blot was used to detect the protein expression of mucin 1 (MUC-1) , occludin , IL-6 , p-JAK2 , and p-STAT3 in colon tissue . Results Compared with the normal control group , the body mass and colon length of the model group mice significantly decreased . The expression of MUC-1 and occludin proteins significantly reduced (P < 0. 01) . The activities of CAT and SOD significantly reduced . DAI score and CMDI score significantly increased (P < 0. 01) . The expression levels of TNF-α, IL-6 , and IL-1βsignificantly increased (P < 0. 01) . The content of MPO and MDA significantly increased (P < 0. 01) . The expression of IL-6 , p-JAK2 and p- STAT3 proteins significantly increased ( P < 0. 01) . Compared with the model group , the body mass and colon length of mice in sulfasalazine group and geniposide medium and high-dose groups significantly increased (P < 0. 05 or P < 0. 01) , the expression of MUC-1 and occludin proteins increased (P < 0. 05 or P < 0. 01) , as well as the activity of CAT and SOD (P < 0. 05 or P < 0. 01) . DAI score and CMDI score in Sulfasalazine group and genipo- side medium and high-dose groups significantly reduced (P < 0. 05 or P < 0. 01) , as well as the expression levels of TNF-α, IL-6 , and IL-1β(P < 0. 05 or P < 0. 01) . MPO and MDA content in Sulfasalazine group and genipo- side medium and high-dose groups significantly reduced (P < 0. 05 or P < 0. 01) , as well as the expression of IL- 6 , p-JAK2 , and p-STAT3 proteins (P < 0. 05 or P < 0. 01) . Conclusion Geniposide maintaines intestinal home- ostasis by regulating the structure of the intestinal flora and improves colitis injury in UC mice by inhibiting the acti- vation of the IL-6/JAK2/STAT3 pathway .