Ulcerative colitis is a chronic relapsing inflammatory bowel disease. Modern research indicates that immune dysregulation resulting from disruptions in circadian rhythm is closely associated with its pathogenesis. Both Western chronomedicine and traditional Chinese medicine（TCM）" treatment based on temporal factors" emphasize the temporal relationship between natural rhythms and human physiology and pathology. The " midnight-noon and ebb-flow " theory represents the concrete application and deepening of TCM " treatment based on temporal factors" within the realm of chronomedicine. This article correlates the onset time of ulcerative colitis with specific periods in the " midnight-noon and ebb-flow"theory：the Mao period（05：00-07：00），when the yangming large intestine meridian of hand is dominant； the Si period（09：00-11：00），when the taiyin spleen meridian of foot is dominant； and the You period（17：00-19：00），when the shaoyin kidney meridian of foot is dominant. According to this perspective，if the disease manifests during the Mao period，the pathogenesis is attributed to dampnessheat accumulation and disorder of qi and blood. Treatment should focus on clearing heat，resolving dampness，and harmonizing qi and blood，using modified formulas such as Shaoyao Decoction or Baitouweng Decoction. If it occurs during the Si period，the pathogenesis involves spleen deficiency with dampness obstruction and disharmony of qi and blood. Treatment should focus on strengthening the spleen，eliminating dampness，and restoring qi and blood，using modified formulas such as Huangya Decoction or Shenling Baizhu Powder. If it presents during the You period，the pathogenesis is characterized by fire failing to warm earth，and consumption resulting in qi and blood leakage. Treatment should focus on warming the kidney and spleen，and securing qi and blood，using modified formulas such as Sishen Pill or Tianhun Decoction. In addition to oral administration of Chinese herbal medicine，comprehensive therapies including acupuncture，herbal enemas，and acupoint application can provide novel insights for the clinical diagnosis and treatment of ulcerative colitis.

Ulcerative colitis （UC） is one of the chronic refractory inflammatory bowel diseases characterized by abdominal pain， diarrhea， and mucus， pus and blood in the stool. In recent years， with changes in human life style and improvements of the diagnosis， the incidence and prevalence of UC have been increasing. The pathogenesis of UC is closely related to intestinal mucosal immune dysfunction， intestinal flora disturbance， and abnormal bile acid secretion. Patients with UC have abnormal bile acid secretion and intestinal flora imbalance. A large number of studies have found that abnormal bile acid secretion inhibits immune function， affects signal transduction， and destroys the intestinal mucosal barrier. Intestinal flora disturbance has an important impact on the occurrence and development of inflammation， immune homeostasis， and stress. Bile acids indirectly or directly affect the structure and function of intestinal flora， and at the same time， they produce secondary bile acids under the modification of intestinal flora， entering the liver through enterohepatic circulation. Therefore， the complex dialogue mechanism of bile acid-intestinal flora axis is closely related to the occurrence and development of UC. Based on the basic theory of traditional Chinese medicine（TCM） and clinical research， it is found that emotion is an important factor that induces this disease， spleen and stomach weakness is the root of the disease， and liver depression and spleen deficiency are the key pathogenesis of UC. Combined with modern medicine and molecular biology research， it is believed that abnormal secretion of bile acids is a microscopic manifestation of liver depression in TCM， and intestinal flora disturbance is the biological basis of spleen deficiency. In the pathogenesis of UC， the imbalanced bile acid-intestinal flora axis is consistent with the pathogenesis of liver depression and spleen in TCM. The exploration of the biological connotation of the pathogenesis of UC with liver depression and spleen deficiency from the perspective of bile acid-intestinal flora axis can better explain the scientific nature of its pathogenesis， which provides new clinical solutions and reliable references for studying the pathogenesis of UC with liver depression and spleen deficiency and finding representative prescriptions to prevent and treat this disease.

Yiyi Fuzi Baijiangsan is scattered from the Essentials from the Golden Cabinet （《金匮要略》） for the treatment of intestinal carbuncles. The whole prescription is composed of Coicis Semen， Aconiti Lateralis Radix Praeparata， and Patrinia scabiosifolia， with the effect of invigorating spleen， warming Yang， clearing heat， removing dampness， and detoxification， which is a commonly used prescription for the clinical treatment of ulcerative colitis （UC）. UC is a chronic nonspecific inflammatory disease with lesions involving the colorectal mucosa， and the etiology is not yet very clear， which is mostly related to genetics， external and intestinal environment， immunity， infection， and other factors. Animal experiments and clinical studies have shown that Yiyi Fuzi Baijiangsan have the advantages of multi-target and multi-faceted treatment of UC. At present， the research mechanism of the treatment of UC is mainly focused on reducing intestinal inflammatory response， anti-colorectal cancer effect， alleviating oxidative stress， repairing the intestinal epithelial cell barrier， improving intestinal flora disorder， inhibiting apoptosis， maintaining intestinal immune balance， etc. Clinically， the combination of modified Yiyi Fuzi Baijiangsan and western medicine has a satisfactory effect， which can significantly improve the relevant clinical symptoms of patients with UC， delay the condition， and improve the quality of life of patients， with the advantages of high safety and small side effects. Its related research provides theoretical support and data support for the clinical prevention and treatment of UC and the follow-up exploration of the mechanism of Yiyi Fuzi Baijiangsan in the treatment of UC， and is also of great significance to the research on the treatment of UC with Chinese medicine. This paper reviewed the prevention and control mechanism of Yiyi Fuzi Baijiangsan in the treatment of UC.