Abstract：Physicians treating ulcerative colitis focus more on spleen yang than spleen yin. This paper discusses the origin and physiological function of spleen yin，ulcerative colitis and spleen yin deficiency，as well as the treatments，methods， prescriptions and medicinals based on spleen yin theory. The analysis shows that spleen yin deficiency is the origin of the disease. Eating disorders，worry and fatigue，six pathogenic factors and pathogenic qi，deficiency due to long-term disease and excessive use of warm dryness can all consume spleen yin，thus causing more deficiency in spleen yin. In the Chinese medicine treatment，the sovereign medicinals are sweet and bland for neutral supplementation，the minister medicinals are to warm the center and boost yin，the assistant medicinals are sour and sweet to form yin，combined with the products of promoting blood circulation and activating collaterals， as well as protecting membrane and promote tissue regeneration， which can achieve good results.