Children like biting fingernails may be caused by bad habits, xenophagia or psychological factors. Parents should observe their children for any abnormalities and avoid adding pressure on them. If abnormalities occur, it is recommended to go to the hospital in time. 1. Bad habits: Children often bite their fingernails, and parents do not intervene and correct them in time, leading to the formation of bad habits. 2. Ectophagia: mainly manifested in the patient will eat some non-food and non-nutritious substances, may be related to zinc deficiency and unfavorable living environment. 3. Psychological factors: if the child is in a state of anxiety, nervousness will appear like biting fingernails, may be related to excessive pressure, environmental factors. If the child appears abnormal psychology, should be timely intervention treatment. Parents should correct the bad behavior habits, observe the child with or without abnormalities, avoid adding pressure on the child, if abnormalities occur, it is recommended to go to the hospital in a timely manner.