Pediatric neutrophil low is caused by infection, congenital agranulocytosis, neutrophils are a kind of human immune cells, but also the body’s immune response to the effect of the cells. Under the action of chemokines and regulatory factors, they can play a role in phagocytosis and release of oxygen free radicals and lysosomal enzymes, as well as killing purulent pathogenic bacteria and some other functions. Viral infections can lead to low neutrophil counts, and if the infection is severe, it can lead to neutrophil deficiency, which can lead to severe bacterial infections. In addition, congenital factors such as agranulocytosis, peripheral agranulocytosis and other diseases can also cause neutropenia in children. To confirm the diagnosis, the first step is to go to the hospital for several routine blood tests, and if necessary, bone marrow tests can also be performed to make a definitive diagnosis.