Cranial defects are partly due to open cranial injury or firearm penetrating injury and partly due to surgical decompression or craniectomy of the patient. In recent years, due to the better results of decompression with debridement in patients with severe traumatic brain injury, the proportion of the resulting cranial defects has increased. Cranial injuries often bring physical and psychological stress to patients, keeping them away from social life. Cranial repair not only restores the normal appearance of the skull aesthetically, but also stabilizes the intracranial environment and facilitates the recovery from neurological injury. Cranial defect manifestation: local swelling, pain at the edge of the defect, intolerable brain pulsation, brain tissue at the defect area sinks into the skull when the patient is upright; brain tissue at the defect area expands outward when the patient is lying down. Cranial defect syndrome: such as severe headache, vertigo, fatigue, irritability, memory loss, depression, decreased tolerance to vibration and sound, etc. Some patients have symptoms that 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 is broken in the skull. According to the degree of damage to the skull level, it can be divided into total defect and partial defect (such as outer plate defect), among which total defect is common. According to the cause of cranial defects, there are congenital cranial defects and acquired cranial defects. Congenital cranial defects are common in patients with meningeal bulge; acquired cranial defects are caused by trauma and intracranial surgery performed by a surgeon for some type of intracranial disease, or by removal of part of the cranial lesion for cranial disease. Currently, PEEK is the ideal material for cranial repair because it has excellent histocompatibility and does not produce rejection, and PEEK has good radiation transmission and does not interfere with postoperative medical examinations. In addition, PEEK is an ideal material for cranial repair because it is comparable to human cranial bone in terms of elasticity, strength, insulation, and stability. Through the above introduction we understand that there are obvious conscious symptoms after cranial defect, such as headache, dizziness or pain at the edge of the bone defect, and later on it can also cause off-site able damage to the nerves of the brain of the patient or even complications. Therefore, early treatment and early recovery.