Ulcerative colitis is a recurrent and refractory disease of the digestive system，which has gradually affected people's normal life and become one of the clinically refractory diseases.However，in recent years，traditional Chinese medicine has given full play to its advantages in the treatment of this disease and received good clinical feedback，which is expected to break through the treatment bottleneck.The two main characteristics of TCM diagnosis and treatment are syndrome differentiation and holistic concept，among which “differentiation” is the basic process of TCM diagnosis and the soul of TCM clinical thinking.“Five differentiation” includes disease differentiation，symptom differentiation，syndrome differentiation，individual differentiation and pathogenesis differentiation.Using the “five differentiation” diagnosis thinking in the prevention and treatment of ulcerative colitis helps doctors in the internal mechanism of ulcerative colitis，development trend，pathology in the specific phase，change law，and primary and secondary contradictions，thus providing more effective theoretical basis and thinking on the basis of traditional diagnosis and treatment and improving the clinical efficacy.