Early training of MRC muscle functional appliance, correcting children's bad oral habits, adjusting lips, jaws and muscles to normal positions, and achieving normal balance; Establish correct swallowing and nasal breathing, remove the external factors that affect the normal development of children's maxillofacial region as much as possible, so that the growth potential can be naturally exerted, thus achieving the purpose of correcting dentofacial deformities and bad habits. MRC muscle functional orthosis is suitable for children aged 3- 15 who are still in the growth and development stage of maxillofacial region. We generally recommend early intervention for children aged 6- 10, and the effect is good. However, there is another one, that is, the anti-jaw, which is what we often call the child of Dibaotian. When the children in Dibaotian are 3-5 years old, we will wear MRC for them as long as they can cooperate.