Fever is one of the common symptoms in children. Most children do not have a fever that stays high for several days, but their temperature fluctuates from day to day, with some having a fever during the day and a normal temperature at night. The fever itself is a protective response of the body against pathogens, which enter the body and the body clears them by mobilizing the immune response, so the fever appears. Common cold fever may last 1-3 days, the baby’s mental appetite state is good, indicating that the disease is not serious, the temperature is not consistent with the severity of the disease. Generally children with viral infection have normal temperature during the day, or light fever, and higher fever at night, which may be due to the fact that during the day the cerebral cortex is attracted by various living things and activities of interest, and excitability suppresses other reactions temporarily (such as fever response is not obvious, or even not responding). However, at night, the organism is at rest, and the infection response that was temporarily suppressed during the day is lifted, plus the baby gets less water at night, and the infant’s body contains a higher percentage of water than that of adults, which affects heat dissipation as long as it is mildly dehydrated, easily leading to easy fever at night. Almost every child experiences fever. As long as the child is in good spirits, which indicates a mild condition, antipyretic medication can be given. If the child is not in good spirits, he or she needs to seek medical attention.