The treatment of cranial defects is to perform cranioplasty, but the timing, method, and materials chosen for the procedure, as well as indications and contraindications, must be carefully considered, especially the patient’s purpose in requesting the repair of the cranial defect, and what problems they hope to solve. This is because the therapeutic effect of simple cranioplasty on functional symptoms, psychiatric disorders and traumatic epilepsy after traumatic brain injury is unpredictable. Usually, if the diameter of the skull defect is less than 3cm, there is no symptom, and after sub-temporal decompression or suboccipital decompression, there are hypertrophied muscles and fascia covering the defect area and forming a tough fibrous healing layer, which can play the role of the original skull to protect the brain, and there is no symptom, so there is no need for cranial bone repair. Defects with a diameter of more than 3cm, especially those located in the frontal area that hinder the aesthetics and safety, often have this or that kind of symptom, such as dizziness, headache, localized tenderness, irritability, restlessness and other manifestations; or the patient has a fear of the defective area of the throbbing, swelling, wall sinking, fear of the sun, fear of vibration and even fear of noisy sounds, often have poor self-control, poor concentration and memory loss; or have depression, Fatigue, reticence and low self-esteem; or due to a large area of missing skull caused by the patient’s skull serious deformity, directly affecting the physiological balance of intracranial pressure, collapse when standing upright, when lying down bulging, concave in the morning, convex at night; or due to the atmospheric pressure directly through the defective area of the role of the brain tissue. Over time, this will inevitably lead to localized brain atrophy, aggravating the symptoms of brain loss, and at the same time, the ventricles on the affected side are gradually expanding and bulging out or deforming towards the defective area. In this case, repair surgery should be considered. In addition, pediatric cranial defects may become larger with the development of brain tissue, the edge of the defect turns outward, and the protruding brain tissue gradually shows progressive atrophy and cystic degeneration, so the pediatric patients need a complete cranium to ensure the normal development of the brain. Currently, the recognized indications for surgery are: the diameter of cranial defect is larger than 3cm, the defect is aesthetic, causing long-term dizziness, headache and other symptoms that are difficult to be relieved, meningeal-brain scar formation with epilepsy (at the same time, canker lesion resection must be carried out), serious mental burden affecting the work and life. Cranioplasty should not be performed on patients with incomplete initial debridement, local infection, intracranial lesions and increased intracranial pressure. In addition, some patients with poor general condition, serious nerve defects, and those who cannot take care of their own life; or those who have large scar in the defective area with thin scalp, should not be rushed to repair, and can be covered with a partial helmet for temporary protection, and then consider cranioplasty when the conditions are ripe. The timing of cranial defect repair should depend on the patient’s systemic and local conditions: closed skull fracture, scalp integrity and injury is relatively light, brain injury is not serious, can be in the depression of the crushed bone fragments at the same time as the removal of the period of cranioplasty. However, we still need to be alert to the possibility of infection after the operation. Generally, cranioplasty can be performed 3-6 months after the wound is not infected, and for infected wounds, depending on the extent and degree of infection, the earliest we can consider repairing the wounds after they have completely healed for more than 6 months. If there is extensive scalp scarring in the cranial defect, the surgery should be staged. Pediatric skull defects should not be repaired before the age of 5 years. Because of the rapid brain development of children, especially within 3 years of age, the head circumference grows rapidly, premature repair will occur after the gap. Although there are bone defects in young children, as long as the periosteum and dura mater exist, the bone can grow again, so there is no urgent need for repair. after 5 years of age, the growth of the skull slows down significantly, and then cranial repair can be carried out.