Background: The etiology and pathogenesis of ulcerative colitis remain unknown. It is very important to develop a proper animal model for understanding the pathology of UC.  Aims: we developed the acute mice dextran sodium sulfate ulcerative colitis and wanted to know the proper concentration and time of dextran sodium sulfate in inducing acute ulcerative colitis.  Methods:Acute colitis was induced by the administration of 3%、5%、8% DSS in C57BL/6 mice, In control,mice drank distilled water. The colonic injury and inflammation were assessed by disease active index (DAI) and histological index (HI) to evaluate the model.  Results: A linear increase in DAI was noted with increasing concentrations (1.50±0.53、7.71±1.38、9.14±1.03 and 9.71±0.61,respectively), and depended on the DSS concentrations( p<0.05 comparing all groups); A linear increase in HI of the distal colon (0、5.19±1.06、6.38±0.91 and 7.75±0.46, respectively) and proximal colon (0、3.50±1.07、5.12±1.55 and 6.62±1.41, respectively ) was noted with increasing concentrations, and depended on the DSS concentration( p<0.05 comparing all groups) ; The mortality increased with increasing (0、3%、5%、8%) DSS concentrations (0、7.10%、28.60%、57.10%,respectively).  Conclusions: DSS-induced acute mucosal injury was dependent on DSS concentration. An ideal acute UC model might be developed by which C57BL/6 mice drank 3% DSS (molecular weight was 36,000～44,000) for five days .