The cause of fingernail biting in children can be caused by psychological factors, zinc deficiency and parasitic infections, which can be treated with general therapy, piperazine phosphate and other medications. 1. Psychological factors: when the child is in a more anxious, tense environment or by scolding, corporal punishment, etc., can be due to psychological factors lead to fingernail biting, remove the triggers can improve. 2. Zinc deficiency: causes taste buds to develop abnormally, resulting in xenophagia. Children are prone to fingernail biting symptoms, you can take oral zinc gluconate to improve the symptoms. 3. Parasitic infections: lead to nutrient absorption disorders, which can lead to fingernail biting symptoms, the symptomatic use of piperazine phosphate can be improved. Children biting fingernails may have other reasons, it is recommended to consult a doctor in time to identify the cause, the cause of treatment, the above medication as prescribed by the doctor.