Abstract: To study the experimental treatment effect of Chang′anning capsules,the rat model of ulcerative colitis（UC） was established by using acetic acid. After the preparation of the ulcerative colitis rat model,the rats were randomly divided into six groups, including normal control group，model control group，western medicine positive control group (SASP),TCM positive control group，small，medium and large dose group of Chang′anning capsules. Each group was treated for three weeks. The normal and model control groups were fed using the standard method. During the study, the general activities and appearance of the rats were observed. After the experiment,blood withdrawal, dissection and pathological section were conducted while examination of the colon mucosa and detection of both the inflammation and immune cells were carried out. In comparison to the model group,the rats′ general states of all treatment groups were better than that of model group in three weeks treatment. Macroscopic observation and histopathological section indicated the marked obvious effect of Chang′anning capsules on UC rats, and there existed no abnormal thickening in the rats′ colon after the treatment of Chang′anning capsules. Leucocyte and neutrophile granulocytes were significantly less than those of the model group (P<0.05),but the T cell subgroup CD4⁺ /CD8^+ was larger than that of the model group (P<0.01),which could indicate that Chang′anning capsules could decrease inflammation and increase the immune function.It was concluded that Chang′anning capsules (higher dose）has significant treatment effect on the experimental ulcerative colitis of rats.