Fever with high white blood cells is usually caused by bacterial infections and diseases of the blood system. When there is a bacterial infection, the patient may have fever and other symptoms, and the increased white blood cells can eliminate the bacteria, thus providing an anti-inflammatory effect. The body’s immune balance is maintained to avoid more serious symptoms. If a bacterial infection is identified, antibiotics can be given. Amoxicillin, cefixime and cefaclor are commonly used clinically. However, not all fever and high white blood cells are caused by bacterial infection. If there is fever and high white blood cells, it may also be due to blood diseases, such as chronic myeloproliferative disease, acute granulocytic leukemia, multiple myeloma. The appearance of this situation should be combined with the patient’s clinical symptoms, signs and relevant examinations to make a comprehensive judgment. Many diseases can lead to increased white blood cells and fever, and it is necessary to go to the hospital in time to avoid delaying the condition.