In winter and spring, children between 6 months and 3 years old are prone to fever; children under 6 months old are less likely to be infected because they are breastfed and have maternal antibodies; children over 3 years old have fewer colds because of their increased resistance; however, they have more chances of contracting infectious diseases because they are more active outside. Pediatric cold and fever is a response of the body to the infected microorganism and is a protective mechanism. High body temperature does not mean serious illness, on the contrary, low body temperature or no fever does not necessarily mean light illness. Weak children suffering from pneumonia, sepsis, shock and other diseases are not feverish, but the body temperature does not rise, poor spirit, poor milk; more likely to misdiagnosis, more likely to critical life. Therefore, high or low temperature should not be used as a criterion to evaluate the seriousness of the disease! After a fever, it is not advisable to rush to reduce the fever and take antibiotics. Generally physical fever reduction is the fastest, and below 38.5 degrees is safe. The first thing after the onset of the disease is to clarify the cause and understand the degree of harm of the symptoms; sometimes the harm of overuse of antipyretics is greater than the harm of the fever itself, and the blind application of antibiotics is also very harmful to children. Parents should observe carefully, the mental state is more important, and the accompanying symptoms are also important for the diagnosis of the disease.