This paper discusses the clinical experience of Professor Li Linggui in treating ulcerative colitis. Professor Li believes that the disease mainly originates from liver depression and spleen deficiency.Spleen deficiency causes dampness and turbidity and qi depression brings about fire and toxicity,which results in internal retention of turbidity and toxicity. This condition may cause the injury of yin,which results in yang nothing to rely on,finally causing the impairment of both yin and yang as well as deficiency of spleen and kidney yang. The main treatment method is removing turbidity and detoxification. The method of eliminating pathogenic factors and treating the branch should be applied in the attack stage and strengthening healthy qi and consolidating the root in the remission stage. At the same time, the method of protecting the stomach and treating both inside and outside should be considered. One proven case is presented.