Objective: To study the Sini Powders and the different compatibilities in intervening experimental ulcerative colitis. Method: The experimental rats were divided into 14 groups and modeled with immunization.The status,colon organization and its pathological changes,thymus index,spleen index,activity of nuclear factor-Kappa B (NF-κB) of rats were observed. Result: All parameters of model group showed significant difference with that of the normal group(P<0.01).Compared with model group(4.40±1.07),the degrees of colonic injury of all drug groups were significantly lower(P<0.01).Compared with the model,pathological changes in colon for Sini powders group(2.80±0.79),Chaishaozhi group(3.20±0.79),Chaishaogan group(3.40±0.70),Chaishao group(3.20±0.79) and Chaizhi group(3.33±0.71)were all evident.The Sini Powders and the different compatibilities could improve thymus index and spleen index.And activities of NF-κB of all drug groups were decreased significantly,especially for the Sini Powders(0.023±0.006)(P<0.01). Conclusion: We speculate that the Sini Powders can intervene with the experimental UC by stimulating the immune organs to excrete the immune cells and inhibiting NF-κB to be activated.Bupleurum and peony,as the monarch drug and the ministerial drug in the prescription,play the important roles.Licorice plays a coordinating role through stimulating thymus cells proliferation as the conducting drug.