The most serious complication after craniotomy is the disease aggravated by the increase of intracranial pressure. First, if rebleeding occurs after craniotomy, if the amount of rebleeding is relatively large, it will lead to the increase of intracranial pressure in patients, and the increase of intracranial pressure to a certain degree may cause brain herniation in patients, which will seriously endanger the lives of patients. Second, after craniotomy, if the patient is complicated by malignant cerebral edema, the consequences of malignant cerebral edema will lead to an increase in intracranial pressure, and the increase in intracranial pressure to a certain degree will also endanger the life of the patient. Third, intracranial infection, because the surgery is carried out in the cranial related operations, there is a possibility of intracranial infection, if intracranial infection occurs, the treatment period is longer, if the intracranial infection caused by the bacillus, its mortality rate is also higher. Therefore, the more serious complications after craniotomy include rebleeding, cerebral edema, and intracranial infection.