Ulcerative colitis (UC) is a chronic, nonspecific inflammatory bowel disease (IBD) characterized by complicated and relapsing inflammation in the gastrointestinal tract. SM934 is a water-soluble artemisinin analogue that shows anti-inflammatory and immuno-regulatory effects. In this study, we investigated the effects of SM934 on UC both in vivo and in vitro. A mouse model of colitis was established in mice by oral administration of 5% dextran sulfate sodium (DSS). SM934 (3, 10 mg/kg per day, ig) was administered to the mice for 10 days. After the mice were sacrificed, colons, spleens and mesenteric lymph nodes (MLNs) were collected for analyses. We showed that SM934 administration restored DSS-induced body weight loss, colon shortening, injury and inflammation scores. Furthermore, SM934 administration significantly decreased the disease activity index (DAI), histopathological scores, and myeloperoxidase (MPO) activities in colonic tissues. Moreover, SM934 administration dose-dependently decreased the mRNA and protein levels of DSS-induced pro-inflammatory cytokines (IL-1β, IL-6 and TNF-α), and the percentage of macrophages and neutrophils in colon tissues. The effects of SM934 on LPS-stimulated RAW 264.7 cells and THP-1-derived macrophages were examined in vitro. Treatment with SM934 (0.8, 8, 80 μmol/L) dose-dependently decreased the production of pro-inflammatory mediators in LPS-stimulated RAW264.7 cells and THP-1-derived macrophages via inhibiting activation of the NF-κB signaling. Our results reveal the protective effects of SM934 on DSS-induced colitis can be attributed to its suppressing effects on neutrophils and macrophages and its inhibitory role in the NF-κB signaling, suggests that SM934 might be a potential effective drug for ulcerative colitis.