Low granulocytes are mainly caused by viral infections, which can lead to an increase in lymphocytes and indirectly to a decrease in granulocytes, as well as some blood disorders. Therefore, when a patient’s blood count indicates a decrease in granulocytes, the diagnosis should be made in conjunction with clinical symptoms and further relevant tests, and appropriate treatment should be taken according to the diagnosis. If the granulocyte decrease is due to viral infection, antiviral and symptomatic treatment is needed, including oseltamivir and abirater. If the patient has decreased granulocytes due to a blood disorder, he/she needs to consult the hematology department for further improvement of the bone aspiration test to clarify the diagnosis and make targeted treatment.