Diarrhea in infants and children is a common pediatric problem and an important issue affecting pediatric health. Diarrhea can lead to severe dehydration and electrolyte disturbance and death. I. Etiology Infants and young children have immature and overburdened digestive systems, poor body defenses, infections inside and outside the intestinal tract, improper diet and hot and cold climate factors are important causes of the disease. Human rotavirus is the most common cause of diarrhea in infants and young children in autumn and winter, easily invading the mucosa of the proximal small intestine and affecting the absorption function of the intestine. The incubation period is 1-3 days, and the onset of the disease is rapid, often accompanied by fever and upper respiratory tract infection symptoms, usually without obvious toxic symptoms. Most children have vomiting at the beginning of the disease, often preceded by diarrhea. The number of stools is increased, within 10 times a day, or up to dozens of times a day, in large amounts, yellowish and watery or egg-flower-like. Symptoms of dehydration and disturbance of electrolyte-acid-base balance are often present. The disease is self-limiting, vomiting stops after a few days, diarrhea is reduced, the duration of the disease is about 3-8 days, a few lasted until several months. Second, the principles of treatment: adjust the diet; control the infection inside and outside the intestinal tract; correct the water-electrolyte disorder; strengthen care to prevent complications. 1.Stop indigestible and fatty food, small amount and many meals, severe vomiting should be fasted for 4-6 hours, generally no need to abstain from water; strengthen nursing care, prevent vomiting and accidental aspiration, change diapers diligently, wash buttocks after stool to prevent episodic urinary tract infection and buttock infection and diaper rash. 2, drug therapy: antibiotic agents: invasive bacterial enteritis are required to use antibiotics, the rest of the diarrhea generally do not need to be applied to diet therapy and supportive therapy; mucosal protective agents: such as montelukast can protect the intestinal mucosa; 3. intestinal microecological regulators: commonly used drugs are lactase, morphine, pepcidone, etc. 3. Fluid therapy: oral rehydration is used for the prevention of dehydration during diarrhea and for children with mild to moderate dehydration without obvious peripheral circulatory disorders; children with moderate or above dehydration and severe diarrhea need intravenous rehydration.