Diarrhea in babies is medically known as “pediatric diarrheal disease”, a group of gastrointestinal syndromes caused by multiple pathogens and factors, characterized by an increase in the number of stools and changes in stool properties. The causes of pediatric diarrhea are complex and can be divided into infectious diarrhea and non-infectious diarrhea. Infectious factors include viruses, bacteria, fungi, parasites, etc.; non-infectious factors include symptomatic diarrhea, allergic diarrhea, food-bait diarrhea, inflammatory bowel disease, etc. When a baby presents with diarrhea with fever, the first thing that needs to be clarified is the cause of the disease, which must be seen in the pediatric internal medicine department for an interview and requires routine blood and stool tests. The most common causes of diarrhea and fever in babies are infectious factors, such as bacterial or viral infections that cause fever in babies; in addition, diarrhea in infants leads to a high loss of body water and a decrease in effective blood circulation, which in turn causes fever. At the same time, the affected baby can be accompanied by more obvious symptoms of dehydration, including dryness of the baby’s skin and mucous membranes, sunken fontanelle, reduced tears and urine, or even no tears or urine. In the case of bacterial diarrhea, active anti-infective treatment is required. The main manifestation of bacterial diarrhea is mucus-like stools or mucopurulent and bloody stools. If the symptoms are not very serious, oral antibiotic treatment can be given; if the symptoms are more serious, intravenous drip antibiotic treatment is needed. If it is caused by dehydration, most of it can be corrected by oral rehydration therapy, and severe dehydration requires intravenous rehydration. The diet of breastfed infants should be continued, with appropriate limitation of the number of nursing sessions or shortening of the duration of each nursing session, and suspension of complementary foods; artificially fed infants can be fed with equal amounts of rice soup or diluted milk or other milk substitutes, and gradually change from rice soup, porridge, noodles, etc. to normal diet. For children with lactose intolerance, add lactase to the diet or remove lactose from the diet. Babies with fever and diarrhea can also be treated with micro-ecological therapy by giving intestinal probiotics or gastrointestinal mucosal protectors such as montelukast. 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 lower than 38.5 degrees Celsius, physical cooling can be used.