When a baby has diarrhea with fever, the first thing that needs to be done is to identify the cause and must be seen in the hospital, which requires routine blood and stool tests. The most common cause of diarrhea and fever in babies is caused by infectious factors. Bacterial or viral infections can cause fever in babies; in addition, diarrhea in babies can lead to more water loss in the body and a decrease in effective circulating blood volume, which in turn causes fever. In the case of bacterial diarrhea, active anti-infective treatment is required. The main manifestation of bacterial diarrhea is mucus-like stools or mucus-purulent blood stools. If the symptoms are not severe, oral antibiotics can be administered; if they are more severe, intravenous antibiotics are required. If it is caused by dehydration, most of it can be corrected by oral rehydration therapy, and severe dehydration requires intravenous rehydration. (1) Oral rehydration solution: It is suitable for those who are mildly or moderately dehydrated. Oral rehydration is not suitable for those with severe abdominal distension, shock, cardiac and renal insufficiency and other serious complications, as well as for premature babies. Oral rehydration is divided into two phases, i.e., correction of dehydration phase and maintenance therapy phase. To correct dehydration, ORS is applied to replenish the accumulated losses, 50 ml/kg for mild dehydration and 50-80 ml/kg for moderate dehydration, which is given orally in small amounts and several times to avoid vomiting from affecting the efficacy of treatment, and the required amount of fluid is taken within 4-6 hours. After the dehydration is corrected, ORS is supplemented with equal amount of water dilution to continue the lost amount, with loss, also can be calculated by 10ml/kg each time. The physiological requirements are selected from low-salt liquids, such as boiled water, breast milk or milk, etc. The body surface area of infants and young children is relatively large and their metabolic rate is high, so attention should be paid to replenishing the physiological requirements. (2) Intravenous rehydration: Intravenous rehydration is recommended for children with severe dehydration. In addition, microecological therapy can also be carried out, giving intestinal probiotics or gastrointestinal mucosa protectors such as montelukast. The diet should also be taken care of. Breastfed infants should continue to breastfeed, limit the number of breastfeeding sessions or shorten the duration of each session appropriately, and suspend complementary foods; artificially fed children can be fed with equal amounts of rice soup or diluted milk or other milk substitutes, and gradually transition from rice soup, porridge, noodles, etc. to a normal diet. For lactose intolerant children, add lactase to the diet or remove lactose from the diet. During diarrhea, continue to eat and give the baby a digestible diet appropriate to his or her age, and do not “fast” as much as possible, as fasting can lead to prolonged symptoms and loss of nutrition. Symptomatic treatment is also important. If the fever exceeds 38.5 degrees Celsius, oral ibuprofen can be combined with physical cooling to reduce the fever; if the fever is below 38.5 degrees Celsius, physical cooling is sufficient.