The process of fracture healing can be divided into three phases: 1 , hematoma mechanization evolution period usually lasts about two weeks, after the fracture there is usually some degree of bleeding at the fracture end, the accumulated blood will gradually be organized and absorbed by the body. Some will gradually become fibrotic and form fibers connecting the broken ends of the fracture, so that the fracture end has initial stability. 2, the original bone scab formation period in the fracture of two weeks after the start, during this period gradually in the fracture end of the initial formation of bone scab in order to stabilize the fracture end. And then after the fracture gap, the original bone scab slowly ossifies, and the strength and stability of the bone scab becomes better and better.3. Bone scab remodeling and shaping period is two months after the fracture, and the formed bone scab is remodeled under the action of biologic stress by osteoblasts and osteoclasts. The bone quality of the part with strong stress will be strengthened, and the bone quality of the part with weak stress will be absorbed accordingly, so as to reach the normal bone shape.