The total number and classification of white blood cells in routine blood tests are important references for clinicians in the diagnosis and treatment of diseases, especially in the diagnosis and treatment of acute fever and infectious diseases in pediatrics, where routine blood tests are often essential to distinguish bacterial or viral infections and the severity of infections. However, in my daily work, I often find that the one-sided analysis of total leukocyte count and classification by some parents or physicians leads to the misuse of antibiotics or the bias of disease severity. I would like to make a brief discussion here and offer my own opinion: 1. The following basic concepts must be kept in mind: 1. Total white blood cell (WBC) and classification (both absolute and relative percentage) values reflect inflammatory indicators, in other words, both infectious and non-infectious inflammation can cause changes in the above parameters. 2. In children with fever in pediatrics, WBC and classification values often reflect infectious inflammation and are also often used as a means to identify bacterial or non-bacterial infections. However, in complex chronic and recurrent diseases (e.g., asthma, allergic cough, allergic bowel disease, etc.) and severe infections with systemic inflammatory reactions (e.g., severe infections caused by various pathogens, infectious shock), the above values must be judged with caution because they are influenced by both infectious and non-infectious inflammation. Infectious inflammation.4 The leukocytes are usually normal or reduced in viral infections, and the proportion of lymphocytes in the classification increases, but the total leukocyte count and neutrophils can be increased in some specific viruses or viral infection syndromes.5 The total leukocyte count and classification, as one of the three important information of blood routine (the other two are red blood cell and platelet count), are also important indicators of blood diseases and bone marrow function. Such as leukemia, leukopenia, etc. Second, the common bias and misconceptions of the current pediatric outpatient clinic on the analysis of total blood count leukocytes are: 1. The normal values of leukocytes and classification of adults are used to judge the laboratory values of pediatric patients. The leukocyte level classification in routine blood tests for pediatric patients varies greatly by age (see table below); leukocytes are mainly divided into granulocytes (including neutrophils, eosinophils and basophils) and lymphocytes (monocytes). The changes in the classification of leukocytes are more prominent in granulocytes and lymphocytes: lymphocytes (L) predominate in about 60% of cases from 4 to 6 days after birth to 4 to 6 years of age, and neutrophils (N) in about 30% of cases; while neutrophils predominate in about 65% of cases from 4 to 6 days after birth and from 4 to 6 years of age until adulthood.