Megacolon is a description of a morphological aspect of the intestines and is one of the common congenital intestinal disorders in children. The diagnosis of megacolon is made when radiologic examination reveals that the diameter of the descending colon, sigmoid colon or rectum is >6.5 cm, the diameter of the ascending colon is >8 cm, and the diameter of the cecum is >12 cm, and congenital megacolon is most common due to intestinal developmental malformations. The occurrence of megacolon is related to genetic factors, most of the lesions occur in the distal part of the rectum or sigmoid colon, common symptoms include abdominal distension, persistent constipation, vomiting, etc., and some patients can also palpate fecaliths and masses in the left lower abdomen. In addition, ulcerative colitis may be complicated by toxic megacolon. The disease usually starts slowly, and should be diagnosed in a timely manner, and if left untreated for a long time, it may evolve into intestinal obstruction and other diseases, which will pose a serious threat to the patient’s health.