Cranial defect at the manifestations: localized swelling, pain at the edge of the defect, intolerable cerebral pulsation, the brain tissue at the defect site is plunged into the intracranial area when the patient is standing upright, and the brain tissue at the defect site is puffed outward when the patient is lying down. What are the causes of cranial defects? Cranial defects are partly due to open craniocerebral injury or firearm penetrating injury, and partly due to surgical decompression or resection of the patient’s skull. In recent years, the proportion of skull defects caused by decompression of the bone flap has increased due to the better results obtained in the treatment of patients with severe traumatic brain injuries. Cranial injuries often bring physical and psychological stress to patients and keep them away from social life. Cranial repair not only aesthetically restores the normal appearance of the skull, but also stabilizes the intracranial environment, which is conducive to the recovery of neurological injury. Cranial defect syndrome: such as severe headache, vertigo, easy fatigue, irritability, memory loss, depression, decreased tolerance to vibration and sound. Some patients’ symptoms worsen with changes in body position. A cranial defect is a disruption of the continuity of the skull and the confinement of the cranial cavity and a hole in the skull. Depending on the degree of destruction of the cranial layers, they can be categorized into total and partial defects (e.g. outer plate defects), of which total defects are the most common. According to the causes of cranial defects, they can be divided into congenital cranial defects and acquired cranial defects. Congenital cranial defects are common in patients with meningeal bulging; acquired cranial defects are mostly caused by trauma and due to certain types of intracranial diseases by the doctor to perform intracranial surgery, or cranial diseases to remove part of the cranial lesions. At present, PEEK material as the ideal material for cranial bone repair is because PEEK material has very good histocompatibility, basically will not produce rejection reaction, PEEK material ray transmissibility is good, does not affect a variety of postoperative medical examination. In addition, PEEK material in the elasticity, strength, thermal insulation, stability and other aspects of performance are comparable to the human skull, is a very ideal cranial bone repair material.