After craniotomy, the main responsibility of cranial bone is to protect the central command “brain”, the human cerebral cortex is the most developed, is the organ of thinking, dominates all activities in the organism, and regulates the balance between the organism and the surrounding environment, so the cerebral cortex is the material basis of advanced neural activities. Once skull defect occurs, human brain will lose the hard protective outer shield, and the brain will be easily injured, such as aphasia, tetraplegia, etc. The serious ones will lose their lives, so skull repair surgery should be done as soon as possible after skull defect. What is the best time to repair the skull after craniotomy? The improvement of cerebral blood flow in the early cranioplasty group is more significant than that in the traditional cranioplasty group; early cranioplasty can significantly shorten the operation time and improve the prognosis of patients without increasing the incidence of surgical complications; the incidence of complications in the early cranioplasty group is significantly higher than that in the late cranioplasty group. Therefore, the best time to do skull repair after craniotomy is about 3 months. Of course, when doing skull repair surgery, the overall assessment of patients’ physical symptoms is needed to see whether they are suitable for surgery and whether there are any contraindications, etc. The specific time is mainly based on patients’ physical condition.