Objective:The observation of the effect of the mediation decoction on serum cytokines IL-4 level of rat models with the ulcerative colitis (UC) liver depression revealed some immunological basis of mediation decoction treatment for UC Liver Depression. Methods: rat models made by the methods of both composition and composite factors of restriction; Detection of the normal group, mediation decoction group, SASP group, model group of serum IL-4 content; and statistical analysis. Results: serum IL-4 content of mediation decoction group was significantly higher than that of the model group. Conclusion: mediation decoction was an effective treatment for a rat model of UC Liver depression. The possible answer is that the increase of increase serum levels of IL-4 plays an important role.