Objective A mouse model of ulcerative colitis with spleen deficiency and dampness syndrome was established, and the role of T lymphocytes in this model was studied. Methods C57BL/6 mice were randomly divided equally into Control, FXY, 3% DSS, FXY+3% DSS and FXY+2% DSS groups. A mouse model of ulcerative colitis with spleen deficiency and dampness syndrome was established by DSS and senna leaf. At the end of moulding, HE staining was performed to observe structural changes in the colon tissue. Elisa assay was performed to detect the concentrations of inflammatory cytokines in the colon tissues. Flow cytometry was used to detect the levels of CD4/CD8 T lymphocytes, Th1/Th2, Th17/Treg cells. Results In the FXY group, the clinical symptoms of mice with spleen deficiency and dampness were mainly diarrhea, and mice with 3% DSS colitis mostly showed blood in stool, while mice with spleen deficiency and dampness colitis in the FXY+3%DSS and FXY+2%DSS groups mostly showed diarrhea and blood in stool, but the survival rate of mice in the FXY+3%DSS group was as low as 50%. Compared with the Control group, body weight, colon length and concentrations of anti-inflammatory cytokines IL-10 and TGF-β1 were significantly lower in the 3%DSS, FXY+3%DSS and FXY+2%DSS groups, while concentrations of DAI, colon weight, colon weight index, colon weight/colon length, pro-inflammatory cytokines TNF-ɑ, IL-1β and IL-6 were significantly increased, and significant ulcer formation and inflammatory cell infiltration were observed under light microscopy. Compared with the Control group, the percentages of CD4, Th1 and Th17 cells in the mesenteric lymph nodes of FXY+3% DSS and FXY+2% DSS groups were significantly increased, while CD8, Th2 and Treg cells were significantly decreased. Conclusion The combination of Senna and 2% DSS could successfully construct a model of mice with ulcerative colitis with spleen deficiency and dampness evidence, showing typical CD4/CD8, Th1/Th2 and Th17/Treg cell imbalance characteristics.