The endoscopic report of ulcerative colitis is characterized by a continuous, diffuse distribution of lesions, starting retrograde from the rectum and extending proximally. Mucosal vascular changes, erosions, and ulcers are seen endoscopically; chronic lesions are seen as mucosal roughness and shortening of the colon. 1. Mucosal vascular changes: blurred, disorganized or disappeared texture, congestion, edema, brittleness, hemorrhage and purulent secretion attachment. 2. Vesicles and ulcers: diffuse vesicles and multiple shallow ulcers are seen where lesions are evident. 3. Chronic lesions: common mucosal roughness, fine granular, inflammatory polyps and bridging mucosa, in the process of repeated ulcer healing, scar formation, colon deformation and shortening, colonic pouch shallow, blunt or disappear. Colonoscopy is one of the most important means of diagnosis and differential diagnosis of ulcerative colitis. The whole colon and terminal ileum should be observed as much as possible during the examination to determine the extent of the lesion, and biopsy should be taken if necessary.