Myofunctional trainers do not have a corrective role, only the role of training muscles to achieve a normal state, myofunctional trainers are useful, and their usefulness is great when choosing the right indications. Normal people’s muscles are more coordinated in the oral state, but some people are mouth-breathing patients, the upper teeth will have anterior protrusion, the upper lip has a downward curvature, and the lower lip may be behind the lower teeth during swallowing. The muscles of this type of patients are not normal, by wearing the myofunctional trainer, it can make the upper lip, lower lip, tongue to reach the normal state, so as to shield to the unfavorable muscle strength, to achieve the normal coordination of the state, so as to achieve the purpose of orthodontic. At present, myofunctional trainers are mainly used for children in growth and development, and their effect on adults is relatively weak. If the patient has muscle problems, without muscle function trainer can also achieve the corresponding effect, as long as the correct muscle training, such as tongue training, lip training to do, can achieve the corrective effect.