Cranial defects are treated by performing cranioplasty, but the timing, method, and materials used as well as the indications and contraindications for surgery must be carefully considered, especially the purpose of the patient’s request to repair the cranial defect and what problem he or she wishes to solve. This is because the outcome of cranioplasty alone is unpredictable for the treatment of functional symptoms of post-traumatic brain injury such as neurological disorders and traumatic epilepsy. Material selection: Cranial defect repair titanium mesh currently available for cranioplasty repair materials are autologous tissue and allogeneic materials, the former using the patient’s own ribs, iliac bone or cranial bone, the latter is polymer and metal and other implant materials. The former is made of the patient’s own ribs, iliac bone or cranial bone, while the latter is made of polymer and metal implants. The specific method of repair can be divided into inlay and overlay. At present, the latter method is being used more and more. The timing of skull defect repair should depend on the patient’s general and local conditions, such as after the removal of collapsed bone fragments for simple depressed fractures, the repair can be completed in one operation at the same time. However, for cranial defects caused by open craniosynostosis, cranioplasty should be considered after the initial debridement and 3-6 months of wound healing. If the open wound is already infected, repair surgery should be postponed until the wound has healed for at least six months. Traditionally, non-degradable bioprostheses have been used only as a filling material for cranial defects. With the development of medical and tissue engineering technologies, various synthetic biomaterials have emerged, but these materials cannot be absorbed by the body after transplantation, have rejection and inflammatory reactions, and are difficult to integrate with the host bone. Currently, domestic cranial bone repair materials Plexiglas, silicone rubber, titanium plate, titanium mesh and other organic materials are used. These materials have disadvantages such as easy aging, easy breakage, not easy to shape or poor biocompatibility, etc. Among them, titanium mesh and titanium plate are easy to conduct heat and electricity, causing patients to have head burning sensation in high temperature environment after surgery, and the price of titanium mesh plate is expensive. For silicone rubber materials, although the biocompatibility is better, but there is a problem of low strength. The ideal bone graft material should have good biocompatibility and integration ability, chemically stable, maintain its shape for a long time after surgery, not easy to slip off and displace, predictable long-term biological properties, easy to shape, easy to contour, and cheap. Metal skull forming sheet such as stainless steel plate and mesh, tantalum plate or titanium alloy plate and mesh have strong anti-pressure performance and good tissue compatibility, but because of the thermal conductivity, sharp edges are easy to penetrate the scalp and have the disadvantage of affecting the X-ray examination, which is yet to be improved; flat plexiglass is heated and shaped as repair material, which has the advantage of convenience and ease of use, but the effect is poor for orbital and nasal root, which have high plastic requirements, and At the same time, it is not the ideal material because of its poor punching strength and easy to break. The plastic self-consolidating material made of polymeric materials methyl methacrylate and styrene copolymer powder plus methyl methacrylate monomer aqueous mixed with each other, has good plasticizing properties, and can be self-cured to form a strong and stable permanent implant, with the advantages of suitable strength, good tissue compatibility, not easy to degrade, and does not affect the X-ray examination. In recent years, some people have added pore-making agents to the above two-component materials to develop plastic microporous artificial skull materials. After implantation, fibroblasts can grow into the microporous implant, which makes the implant fuse with the tissue and has the tendency of calcification and ossification, so it can be considered as a more ideal material for cranial repair. In addition, new cranial bone implants made of mesh-reinforced silicone rubber cranial plate, hydroxyapatite or ceramic materials also have good performance in cranial defect repair. Indications for surgery: 1, skull defect larger than 3cm in diameter. 2.Aesthetics of the defective area. 3.It causes long-term dizziness, headache and other symptoms that are difficult to relieve. 4, meningeal-brain scar formation with epilepsy (need to perform epilepsy focal resection at the same time). 5.Severe mental burden affecting work and life. For patients with incomplete initial debridement, local infection, intracranial lesions and increased intracranial pressure, skullplasty should not be performed for the time being. In addition, some patients with poor general condition, serious neurological defect and unable to take care of themselves, or those with thin scalp and large scar in the defect area should not be repaired hastily, and can be temporarily protected with a local helmet, and then consider the surgery after the conditions are mature. There are many kinds of materials for skull repair, each with its own advantages and disadvantages. Although autologous bone has little tissue reaction, it needs to be operated in both the bone donor area and bone graft area, which increases the patient’s pain and has poor plastic surgery results. Some people bury the bone fragments removed by decompression of the large bone flap under the abdomen as a future repair, because of the need for two surgeries, and the bone fragments are often absorbed and become smaller, resulting in loose concave, and the use of allogeneic bone because of refrigeration in the bone bank, increasing the chance of contamination, foreign body reaction is also greater, so they have been used less. Surgical method: Under local or general anesthesia, the scalp incision is curved and the blood supply to the basal part of the flap is fully ensured. When separating the scalp, do not damage the deep dura mater to avoid postoperative fluid accumulation. When using the overlay method of repair, the periphery of the bone defect area does not need to be trimmed and the bone coat does not need to be cut, and the defect area can be covered with an implant slightly larger than the defect, and the surrounding area can be fixed to the bone coat with thick silk. However, it is necessary to use strong, good quality and thin surrounding material to match the shape and curvature of the skull. If the inlay method is used, the bone coat should be cut and trimmed along the edge of the bone defect, and then the appropriately cut implant should be inlaid on the bone defect, and the surrounding holes should be fixed on the bone edge with thick wire. Care should be taken not to open the frontal sinus when performing inlay repair in the forehead to avoid infection. After surgery, the scalp should be sutured in layers, without drainage and with appropriate pressure bandage.