Shengjiaxin operation is a long arc operation of mandibular angle, which is safe and effective. The bone thickness of the mandibular angle part looks like the width of the chin. This surgical method is not to remove all the bones, but to peel off the outermost periosteum of the three-layer structure, so as to reduce the thickness of the mandible and narrow the wide square chin. This is a necessary operation to shape the melon face from the front.