Cranial defects are mostly due to surgical treatment, traumatic defects and congenital cranial defects. And cranial defects not only affect the cosmetic aspect. In severe cases, they can also pose health risks to the patient. Cranial defect repair to meet the defect area greater than 3 * 3cm; is the scope of surgery can be carried out. There is also a serious defect that affects the appearance of the skull can also be carried out cranial bone repair surgery. So it depends on the individual situation to choose. For example, in children, some of the skull defects will heal later and do not require surgical treatment, regardless of the size of the defect. Therefore, it is advisable to go to the hospital for an interview and consult a doctor to decide whether or not the defect needs to be repaired. The main reason for repair is the defect created by removing the bone flap in craniocerebral trauma and brain surgery (mainly acute aneurysm, cerebral hemorrhage, etc.). Due to the change in shape of the cranial defect area, the scalp is subjected to atmospheric pressure, which causes it to sink in and compress the brain tissue. In order to restore the airtightness of the cranial cavity, to keep the physiological intracranial pressure stable and to alleviate the cranial defect syndrome. To solve the defect area without effective protection of brain tissue, blood supply obstacles, cerebrospinal fluid circulation abnormalities and other problems. Currently PEEK material becomes the implant material for cranial bone repair. The material has better histocompatibility. Higher comfort and enhanced thickness. It is similar to human skull. Especially for pediatric patients, it is better adapted to the growth and development of the human autogenous cranium. And it will have a lower rate of infection and rejection. Importantly, the polyether ether ketone material is a material that can be three-dimensionally plasticized, and it can be three-dimensionally customized according to different patients’ conditions, which can really restore the physiological structure of the skull perfectly. Therefore, it is necessary that patients with cranial defects should go to regular hospitals in time to choose appropriate materials for cranial bone repair for safety reasons.