Leukocytosis includes physiological increase and pathological increase. Physiological increase has no effect on patients, while pathological increase may be a manifestation of inflammation, which is a normal reaction of the organism, and may lead to stagnation of leukocytes when significantly increased, affecting blood circulation and blocking small blood vessels. The reference value of leukocyte count in normal adults is 4.0×10∧9 cells/L. The increase in leukocyte count in infants and pregnant women is physiological and has no effect on the patient; usually, when the patient’s organism is inflamed, leukocytes can increase, which is the normal response of the organism to inflammation and may lead to fever and general discomfort, which can be recovered after active anti-inflammatory treatment; in blood system diseases, such as acute In blood system diseases, such as acute or chronic granulocytic leukemia, leukocytes can be significantly increased. In conclusion, leukocytosis is mostly an inflammatory response of the body, and hematologic disorders should be considered if there is a significant increase.