Orthodontic treatment can change mouth breathing, applying muscle function orthodontic appliances, such as MRC, can break the bad habit of mouth breathing, and continuously improve the function of the muscles around the mouth, fixed orthodontic treatment can widen the narrow dental arch, and lift the condition of severe crowding of teeth, continuously applying orthodontic force can improve the situation of lip tilt of upper anterior teeth, mandibular retraction, and the upper and lower teeth can not be closed, and together with the application of extraoral arches and other devices can control the maxillofacial Vertical and sagittal growth. When oral respiration is accompanied by severe maxillary protrusion and mandibular retrusion, orthodontic treatment should be combined with integrated surgical procedures.