Mesenteric lymphadenitis is a non-specific inflammation of mesenteric lymph nodes, mostly seen in children, and is one of the common causes of acute abdominal pain in children. Because of the rich lymphatic drainage of the distal ileum, there are many mesenteric lymph nodes in the ileo- and colonic regions, and the contents of the small intestine stay longer in the distal ileum due to the ileocecal valve, toxins and bacterial metabolites are easily absorbed by the mesenteric lymph nodes of the ileum. Therefore, acute mesenteric lymphadenitis mostly occurs in the mesentery of the distal ileum. The disease is mostly caused by viral infections, the common viruses are echovirus and coxsackievirus; very few cases are caused by bacterial infections, the bacteria are mostly Streptococcus haemolyticus, followed by Staphylococcus aureus, and Salmonella can also cause the disease. In addition, lymph nodes are immune organs, and allergic factors can also cause lymph node enlargement. 2, clinical manifestations The disease is often complicated in the course of acute upper respiratory tract infection, or secondary to intestinal inflammation. The diagnosis of mesenteric lymphadenitis has become more and more common in recent years with the popularization of high frequency ultrasound. Children mostly complain of abdominal pain located around the umbilicus, paroxysmal or spasmodic pain is common, usually without rebound pain and muscle tension; abdominal pressure pain is not fixed and can move with position changes; enlarged lymph nodes can be found on ultrasonography. 3.Diagnosis of mesenteric lymph nodes is made by ultrasound, which is only an imaging diagnosis. Clinical diagnosis needs to exclude the following: ①Acute appendicitis. ②Acute tuberculous mesenteric lymphadenitis. ③Meckel’s diverticulitis. ④ Crohn’s disease. The focus is to exclude diseases that require surgical treatment by physical examination. 5. Treatment Antispasmodic treatment for this disease is ineffective. Apply antiviral drugs for the cause. Antibiotics can be added if there is a basis for bacterial infection. Dietary regulation is especially important. Regular diet, do not exercise strenuously before and after meals. Do not eat any snacks, do not drink milk, eat eggs, fish and shrimp and other foods that can cause intestinal allergies for the time being.