A child’s constant crooked mouth may be related to habits, congenital dysplasia, facial nerve palsy and other factors. 1. Habits: If a child’s crooked mouth can be independently controlled, it is generally considered to be related to the child’s habits, such as speaking with a large range of mouth movements. And children are in the stage of strong imitation, the child may see the surrounding people or toys appear crooked mouth expression, so as to imitate. 2. Congenital dysplasia: If a child is born with a crooked mouth, it is necessary to be alert to congenital abnormalities in the development of localized facial muscles or facial nerves, or abnormalities in the development of the central nervous system. When the facial muscles, facial nerve or central nervous system development is impaired, it is impossible to dominate the mouth correctly, thus the manifestation of always crooked mouth. 3. Facial nerve palsy: If the child’s immunity and resistance are relatively poor, he or she may be infected by pathogenic microorganisms in the surrounding environment, which may cause facial nerve palsy, resulting in the manifestation of a crooked mouth. Children always crooked mouth may also be seen in brain tumors and other causes, there may be other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.