There are more causes of granulocytopenia, and the main categories are as follows: 1. Congenital factors: Some patients have granulocytopenia due to genetic problems or some chromosomal problems, and the condition of such patients is often more serious. Patients may often have fatal infections and sepsis since birth, and may even have other systemic manifestations, such as problems with thymus development or malformations of some organs; 2. Acquired factors: the most common may be viral infections, such as early childhood emergencies, for which patients can wait for their gradual recovery. Some other causes can also lead to granulocytopenia, such as the patient’s choice of ordinary antipyretic drugs, as well as some Chinese medicines, antiviral drugs, anti-thyroid drugs may cause granulocytopenia. Since there are many causes of granulocytopenia, it is important to identify the causes of granulocytopenia and to classify the patient’s condition.