Children always bite fingernails may be bad habits, psychological factors, ectophagy and other causes. 1. Bad habits: children’s imitation ability is strong, deliberately imitating the surrounding children or TV characters gnawing fingernails, will form the bad habit of biting fingernails, parents should be given timely correction. 2. Psychological factors: children have some psychological problems, insecurity, or anxiety, etc., will often gnawing fingernails, parents should be more with the child to communicate, more to give the child psychological comfort, avoid excessive reprimanding the child, if necessary, need to be timely consultation in psychiatry. 3. Ectophagia: the cause of this disease is unknown, may be related to nutritional deficiency, mental illness or lack of family education, etc., the child will not only chew nails, but also may eat non-edible, non-nutritive items, this time need to go to the psychiatry, gastroenterology or pediatrics in a timely manner to the clinic. Prolonged nail biting may seriously affect the growth and development of the nail bed and cause nail deformity. If the child always bites his fingernails and the parents cannot determine the cause, or if the child still bites his nails after correction, or if the nails are already deformed, it is recommended that the parents bring the child to the regular hospital for consultation to determine the cause of the problem and then give targeted treatment.