Cranial defects can have a great impact on health if not repaired, and can even be life-threatening and affect life expectancy in serious cases. If the skull is defective, the brain tissues inside the skull lack the necessary protection and are easily injured; the skull defect makes the intracranial pressure abnormal, the pressure inside and outside the skull is connected, which is not conducive to the circulation of cerebrospinal fluid, and some functions of brain tissues may be restricted; in addition, the collapse caused by the skull defect also affects the aesthetics. In cranial defects, the loss of bone flap protection and atmospheric pressure can cause ipsilateral cerebrospinal fluid circulation disorders and decreased cerebral blood flow, leading to potential brain tissue damage. Large cranial defects can easily cause deformation and displacement of brain tissue, enlargement of the ventricles, and disturbance of water flow in the brain parenchyma, which can affect the production, absorption and circulation of cerebrospinal fluid, resulting in complications such as traumatic hydrocephalus and cerebral bulge. Maintaining the integrity of the dura is the protection of the brain, so it is important to choose a suitable material for repairing cranial defects. The PEEK material can be reconstructed in three dimensions, 3D printed, and highly restored to the physiological structure of the skull, and the material is histocompatible and does not produce any rejection. Very ideal cranial repair material, PEEK material can be perfectly combined with their own cranial bone. There is a latent danger of long-term cranial defects, and patients should not take it lightly and should go to a regular hospital for cranial repair in a timely manner for early recovery.