It is not normal for patients to have fever after craniotomy, but it is a relatively common complication after surgery. The following reasons are more common for patients to have fever after craniotomy: 1. The most common one is lung infection, because craniotomy requires tracheal intubation and general anesthesia, and the sputum in the respiratory tract cannot be discharged at this time, which will lead to lung infection after a long time. In addition, the patient is confused after surgery and cannot cough or cough up sputum on his own, which further aggravates the lung infection. The fever will occur after the lung infection.2. The more common cause is that after craniotomy, the bloody cerebrospinal fluid stimulates the hypothalamic thermoregulatory center, causing central fever.3. There is another cause, which may be the long-term urinary tract intubation, leading to fever caused by urinary tract infection.