The possible causes of normal blood count but fever include viral infection, immune diseases such as rheumatic fever, absorptive fever, endocrine system diseases, neurological diseases, autonomic dysfunction and so on. 1. Viral infections: such as EBV, rhinovirus, adenovirus, etc., after infecting the human body, the blood test will not show obvious changes, but will cause fever symptoms. 2. Immune diseases: such as rheumatic fever, absorbing fever and other diseases, the body has autoantibody immune response, which will lead to increased antigen and antibody reaction in the blood, thus causing fever, the patient may also be due to food allergy triggered by immune response, resulting in skin allergic reactions such as erythema, can also appear temperature rise, the fever caused by this case will not cause changes in the blood routine. 3. Endocrine system diseases: such as hyperthyroidism, thyroid hormone secretion is too high, will promote the body to produce heat, and blood routine is not abnormal. 4. Neurological disorders: When cerebrovascular disease and neurological disorders occur, damage to the hypothalamus, the center of thermoregulation, may lead to an abnormal increase in body temperature. 5. Autonomic dysfunction: the spinal cord may compress the nerves, leading to autonomic dysfunction, body temperature regulation point rises, triggering fever symptoms, the fever in this case no blood routine change performance. Fever with normal blood count may also be caused by other reasons, such as tumors, blood diseases, etc. It is recommended to consult a doctor as soon as possible for a clear diagnosis and specific treatment.