Distraction osteogenesis (DOT) is a specific form of clinical tissue engineering in which bone is surgically severed, an extender is placed and pulled at an appropriate rate to guide the formation of new bone for the purpose of bone lengthening. I. The development process of traction osteogenesis was first applied by Ilizarov in 1951 in the treatment of long bone fractures in humans. 1973, Snyder first reported the application of extra-oral lengtheners to repair bone defects in mandibular defects in experimental dogs with good results. 1977, Michieli applied intra-oral lengtheners to lengthen the mandible of experimental dogs by 15 mm. In 1992, McCarthy reported the clinical application of lengtheners in the treatment of craniofacial deformities. II. Principle: The traction force gradually applied to living biological tissues can create tension, and this tension can stimulate and maintain the regeneration and growth of certain tissue structures. Traction osteogenesis means that under the action of traction force, a continuous, slow force is generated between the bone segments of the truncated bone cortex, and this force will promote the regeneration and growth of bone tissue and soft tissue around the bone, thus forming the simultaneous growth of new bone and soft tissue around the bone between the truncated bone segments. Therefore, while applying this technique to correct the skeletal deformity, it also corrects the accompanying soft tissue deformity. The treatment of traumatic and tumor resection can cause a large amount of bone tissue and soft tissue defects in the jaw. In the past, bone grafting was often used for repair, but in cases where the defect is too large and the surrounding soft tissue is less elastic, the grafted bone is often insufficient to completely restore the morphology of the mandible. Traction osteogenesis technique can lengthen the remaining mandibular bone block or free graft, expand the soft tissues, and provide a good foundation for the reconstruction of the teeth, with good results in clinical practice. After trauma, due to conservative therapy, or incorrect surgical method, or complications of maxillofacial fracture, or severe intracranial and abdominal trauma that postpone the treatment for occlusion, etc. often lead to occlusal deformity, all can be treated with lengthening device, and the lengthening distance can be up to 20-30mm, and the patient’s occlusion and facial morphology are significantly improved than before surgery. 2, congenital maxillofacial deformity correction treatment cleft lip and palate is the most common congenital deformity, a significant proportion of patients (25%-60%) accompanied by more serious midface dysplasia, the conventional application of orthognathic surgery, but due to the limitations of orthognathic surgery, often can not completely correct the deformity, and there is often recurrence after surgery. The application of traction osteogenesis has greatly improved this situation. For maxillary dysplasia, in both adults and children, Le Fort I, II or III osteotomies are performed as needed for treatment, with placement of an extender and, depending on the situation, simultaneous bone grafting. Bone lengthening results can be achieved relatively easily with 10-15 mm of traction and is less affected by lip scarring. The incidence of hemifacial shortening is second only to cleft lip and palate in congenital malformations, also known as first and second cheek arch syndrome. The main goal of applying the distraction osteogenesis technique for hemifacial shortening is to lengthen the mandibular ascending branches and the body to make the occlusal plane as horizontal as possible. This approach is an alternative to complex orthognathic surgery and has been used extensively in recent years, significantly changing the concept of reconstructive surgery for mandibular dysplasia and becoming an efficacious and reliable method of treating this deformity. In summary, the distraction osteogenesis technique, as a relatively new technique, has its unique advantages in the treatment of maxillofacial deformities. The intraoperative application of endoscopy and preoperative computer-aided design can further reduce surgical injuries and enhance the accuracy of postoperative results, making the distraction osteogenesis technique more and more widely used.