Children love to bite nails may be due to bad habits, nervous tension and other physiological factors, or consider the lack of micronutrients, xenophagy and other factors. 1. Physiological factors: If parents do not correct the children’s bad habits in time, it will lead to nail biting. Some children may also bite their nails to relieve tension due to nervousness. Generally, children do not have other uncomfortable symptoms, is a normal phenomenon. 2. Lack of micronutrients: If children are picky eaters and partiality, improper addition of complementary foods, and lack of micronutrients in food, it may lead to nail biting in children. 3. Ectophagia: The etiology of ectophagia is not yet clear, and it may be caused by nutritional deficiencies, intellectual developmental disorders, lack of effective parental supervision and other factors. Children may bite non-food items consciously or unconsciously, and some of them may bite their nails. There are many causes of nail biting in children, and parents are advised to bring their children to a regular hospital to find out the cause of the disease.