The incidence of delayed healing and non-union is high due to the low surface soft tissue coverage and poor blood flow in the middle and lower third of the fracture. It is of practical significance to compare the clinical efficacy of different treatments, analyze the causes of internal fixation failure, and discuss the corresponding preventive measures. The principles and methods of early AO/ASIF fracture surgery, the mechanical properties of internal fixation, and the absolute stability of all fracture blocks; subsequently, it was found that the osteoporosis or accelerated remodeling of the Harvard system after plate fixation was not due to stress protection but to the destruction of the blood flow of the bone, which is particularly important in the treatment of long tubular bones, especially tibial fractures. Accelerated Harvard’s system remodeling is also present along the endosteum in long bones fixed by intramedullary nailing, and these remodels occur in parallel with the distribution of dead bone produced during the reaming and the driving of the intramedullary nail; only viable bone heals in the presence of relative stability, because only viable bone can overcome the effects of activity and achieve stability and thus bone healing through the formation of bone scabs. Considering the fact that manipulation of the internal fixation and fracture fragments disrupts their blood flow and may lead to non-healing, and the shift from an emphasis on absolute stability to an awareness of the need to protect the blood supply and the biomechanical requirements of the different parts of the bone, intramedullary nailing with locking is increasingly used in the treatment of long tubular bones, especially in the lower extremity. The surgical operation of intramedullary nail with locking is far away from the fracture end, which causes little disturbance to the bone and surrounding soft tissues, and is a “minimally invasive technique” for fracture treatment. The bone debris produced during the expansion of the marrow is a good material for bone grafting; however, the intramedullary nail is not an absolutely strong fixation, and the presence of small movements at the fracture end during active limb movement or partial weight-bearing is conducive to bone scab production and increases the firmness of the early fracture healing. Compared to intramedullary nailing with locking, compression plate fixation, in addition to more extensive periosteal stripping and interference with periosteal blood supply, also has soft tissue stripping, which affects postoperative rehabilitation and joint movement due to the large area of injury. The stability of the external fixation bracket is often less than that of the intramedullary nail or the compression plate, so the rate of delayed healing of this group of fractures is higher, and it is easy to complicate the deformity healing; however, the operation is simple and has more advantages, especially in the treatment of Gustilo’s IIIb degree injury, the external fixation bracket has obvious advantages. In addition to its supportive role, surgical treatment of tibial fractures maintains the repositioned position, prevents fracture displacement, and allows the fracture to maintain its anatomic and functional integrity early for healing. The correct choice of surgical approach is often a key factor in determining the prognosis, and clinical indications should be strictly controlled. The application of intramedullary nailing, especially closed penetration nailing for fractures, allows for less soft tissue exposure and provides good stability; the muscles and fascia surrounding the fractured bone protect the blood supply around the fractured bone, which facilitates the revascularization of the injured bone and the formation of epicondylar scab, making the fracture easier to heal. Internal fixation with locking intramedullary nail is suitable for transverse, short oblique and spiral fractures of the femur and upper middle tibia; if used for comminuted or long tubular middle and lower fractures, it is likely to cause postoperative pin bending, limb shortening and rotational deformity. For a long time there has been much controversy about intramedullary nailing for open fractures. With the increased application of internal fixation, a large number of clinical studies have shown that intramedullary nailing can still be used for Gustilo Ⅰ and Ⅱ degree open tibial fractures; for Ⅲa degree open fractures, limited reaming or non-reaming intramedullary nailing can be performed, but should be used with caution; Ⅲb degree open fractures are contraindications to the application of intramedullary nailing. Data show that non-expandable intramedullary nailing with locking nails for Gustilo I and II degree open fractures has a high bone healing rate and good functional recovery, while the infection rate is similar to other methods and can be the preferred method of internal fixation. In addition, the locking intramedullary nail has its unique advantages in the treatment of non-union of fractures: the use of closed nailing technique, less trauma and low infection rate; the application of anti-rotation nails at both ends of the fracture provides a stable mechanical environment for the fracture; the treatment of sclerotic non-union can achieve healing without bone grafting as long as the fracture end is stabilized after marrow expansion. With the increasing application of various clinical fixation devices, the complications are also on the rise. The high rate of complications in this group may be related to the fact that the statistics include cases transferred from outside hospitals due to failure of internal fixation; given the small number of cases collected by the authors, it is not yet possible to compare the complications in each group. The data showed that the main complications included bone discontinuity, deformity healing and joint stiffness; among them, bone discontinuity was caused by various factors, including poor repositioning, plate fracture, screw loosening and breaking, failure of intramedullary nail locking, splitting of the fracture end due to nail penetration, osteomyelitis of the trauma, and premature weight-bearing. Delayed fracture healing can be caused by poor quality of internal fixation materials, destruction of blood flow during internal fixation, difficulty in controlling the appropriate pressure, bone defect without bone grafting, stress masking after internal fixation, and foreign body reaction; postoperative infection, incorrect functional exercise methods, and bending and breaking of stress-concentrated plates and intramedullary nails due to premature weight bearing are also important factors leading to delayed fracture healing.