There are many kinds of risks of craniotomy, mainly including the following: First, bleeding, all surgeries face the risk of bleeding, craniotomy is especially serious bleeding, because the brain tissue is very rich in blood supply, the blood supply to the brain accounts for about 1/5 of the whole body blood supply, that is, 1/5 of the whole body blood is used to supply the brain, in the time of brain surgery, will face the risk of bleeding. Second, the risk of intracranial infection, through the process of surgery, bacteria are planted inside the brain to form foci of infection. Third, the damage of neurological function, postoperative patients appear coma, hemiplegia, aphasia, hearing loss, even deafness, walking impairment and a series of other problems, may be related to the intraoperative brain tissue damage. Fourthly, hematoma in the postoperative area, after craniotomy, it may be possible to review the cranial CT in 2-3 days and find a hematoma in the area where the surgery was done, and the patient shows a series of problems such as poor mental status, coma, and even seizures, which may face another surgery. Long-term bed rest after surgery may lead to pneumonia, including acute myocardial infarction of the heart, induced coronary heart disease, including venous thrombosis of both lower extremities, a series of medical problems, including stress ulcers, gastrointestinal bleeding and other problems. Fifth, the brain tissue may be stretched during the operation, including the effects of the cerebral blood vessels of the ergodic brain, and the patient may face severe cerebral edema after the operation, and severe cerebral edema may require decompression of the bone flap. These are the main risks of craniotomy.