Abstract: Objective To compare the efficacy between metformin and mesalazine in the treatment of experimental colitis in mouse models. Methods Thirty-two C57BL/6 male mice aged 6-8 weeks were randomly divided into the control, dextran sulphate sodium （DSS）, DSS+mesalazine and DSS+metformin groups, with 8 animals in each group. In the control group, the animals were given ad libitum access to autoclaved double-distilled water and oral gavage of 0.2 ml PBS daily. C57BL/6 male mouse models were induced by 3% DSS. In the DSS group, the mice were given ad libitum access to 3% DSS and oral gavage of 0.2 ml PBS daily. In the DSS+mesalazine and DSS+metformin groups, the animals were given ad libitum access to 3% DSS, and oral gavage of 100 mg/（kg·d） mesalazine or metformin. The body weight, colon length, disease activity index （DAI）, histopathological changes and the expression levels of pro-inflammatory cytokines were evaluated in each group. Results Compared with the DSS group, mice treated with DSS+metformin or DSS+mesalazine experienced significantly less body weight loss,lower DAI scores, lower histopathological scores and lower expression levels of pro-inflammatory cytokines（all P < 0.05）. No significant difference was noted between the metformin and mesalazine groups（all P > 0.05）. Conclusion Metformin can ameliorate DSS-induced experimental colitis in mice, which yields equivalent efficacy to that of mesalazine.