When the patient has persistent or recurrent diarrhea and mucopurulent stools, the diagnosis can be made according to the following criteria on the basis of excluding infectious colitis such as bacterial dysentery, amoebic dysentery, chronic schistosomiasis, intestinal tuberculosis and other diseases such as colonic Crohn’s disease, ischemic colitis and radiological colitis: ① those with the above typical clinical manifestations are clinically suspected and further examination should be arranged. ②Any one of the clinical manifestations and colonoscopy or barium enema examination at the same time can be diagnosed as this disease. ③If coupled with the characteristic manifestations of pathological examination in mucosal histological examination or pathological examination of surgical resection specimens, the diagnosis can be confirmed. ④In initial cases, those with atypical clinical manifestations and colonoscopic changes, the diagnosis of ulcerative nodes is not made for the time being and must be followed up for 3-6 months to observe the attacks. ⑤ Mild chronic rectal and sigmoid colitis found by colonoscopy cannot be equated with ulcerated nodes, and changes in the condition should be observed and the etiology carefully searched.