Children always bite the lower lip may be related to physiological reaction, imitation, nervousness and so on. 1. Physiological reaction: young children’s sucking instinct, generally with the growth of the age of the month, the sucking reflex gradually weakened or disappeared, the habit of biting the lower lip will gradually reduce and disappear. 2. Imitation: Some children will imitate others when they see other children doing this, forming a bad habit. This is actually a normal psychological feedback from the child. 3. Nervousness: When a child encounters difficulties or is in a state of chronic nervousness and anxiety, psychological pressure or lack of self-confidence, he or she will bite the lower lip to relieve the nervousness and anxiety. Children always bite the lower lip can also be seen in other reasons, it is recommended that timely medical treatment, follow the doctor’s instructions for relevant examinations, in the doctor’s help to clarify the cause, and targeted treatment or treatment.