Nail biting in children may be caused by bad habits, psychological factors and lack of nutritional elements. 1. Bad habits: due to the child’s strong ability to imitate, there are people around the nail biting crowd, the child may deliberately imitate, will frequently bite nails, parents should be given timely correction. 2. Psychological factors: the child’s body is overly anxious, nervous, or often reprimanded by their parents, they will bite their nails to relieve their bad mood, parents should pay more attention to the child’s physical health, and more communication with the child. 3. Lack of nutrients: When the child’s body lacks nutrients, such as zinc, iron and other trace elements, it will make the child bite his nails frequently, which will seriously affect the child’s physical development. If a child bites his or her nails frequently and parents are unable to identify the cause, it is recommended that the child be taken to a doctor for examination and treatment.