Children love biting nails may be caused by bad habits, mental and psychological factors, or pathological factors such as lack of trace elements, allergies and so on. 1. Bad habits: simple nail biting may be a bad habit, which can be corrected in time and disappear. 2. Psychological factors: such as anxiety, nervousness, insecurity and so on may lead to children love to bite their nails, this time we need to timely psychological intervention, more communication with them. 3. Pathological factors (1) Lack of micronutrients: zinc and iron deficiency caused by picky eating and partiality of food, especially iron deficiency anemia, can cause children to bite nails and other manifestations of xenophagia. (2) Allergy: some naughty children’s fingers are often in contact with mud, sand, soil and other skin damage, resulting in allergic peeling at the fingernails, like to bite them off. Children love to bite nails may also have other reasons, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.