Interleukin (IL)-33, a member of the IL-1 cytokine family, is associated with autoimmune diseases including inflammatory bowel diseases (IBD). A few studies on animal models have shown that IL-33 can suppress Th1 cell response and improve Th2 cell response in mesenteric lymph nodes (MLN) and sera. However, there is little data published about the effect of IL-33 on Th17 cell in and Th1/Th2 cell in colon lamina propria. The aim of this study was to investigate the effect of IL-33 on Th17 cell in colon lamina propria of mice with dextran sulfate sodium (DSS) induced chronic colitis. We studied the influence of IL-33 on colonic tissue injury and clinical symptoms of colitis. The T cell subsets were measured by flow cytometry and the production of cytokines secreted by lamina propria lymphocytes (LPL) was measured by Enzyme-Linked Immunosorbent Assay (ELISA) and quantitative real-time PCR. We have found that rIL-33 treatment led to a significant alleviation of DSS induced chronic colitis as evidenced by 1) alleviation of weight loss, DAI, macroscopic changes and histological score; 2) down-regulating the rates and absolute cell numbers of Th17 and Th1 cell in LPL; 3) inducing secretion of lower levels of IFN-γ and IL-17A. It is therefore concluded that IL-33 may play a therapeutic role in DSS-induced chronic colitis in mice by suppressing Th17 response and switching Th1 to Th2 response.