I often hear parents say that their children never cut their nails, but that they bite them unevenly before they grow. This kind of behavior is called nail biting fetish in children who are constantly biting their nails with their teeth without self-control. The danger of nail biting is not only the epidermis of the finger, so that the nail edge bleeding, nail deformity, but also easy to incur nail fetish and nail infection, and oral infection with each other. Nail biting can also cause resorption of the gums, cracks in the incisor margins, and even misaligned teeth and gum infections. The bad habit of nail biting can also be reprimanded and ridiculed by parents and classmates, affecting children’s physical and mental health and social interaction. Stress and anxiety are important causes of nail biting in children. Such as the pressure of learning, teacher’s reprimand, parental scolding and punishment, family discord, disputes among classmates, noisy environment, etc. will prompt children to bite their nails. In turn, a lonely personality and unstable emotions can aggravate the symptoms. Some children bite their nails when they are highly concentrated, such as when they are concentrating on watching exciting TV, listening to a lively story, doing homework, trying to figure out what to do, or looking for something. Some are caused by imitating the nail-biting actions of others, and such children often have nail-biting fetishists in their families. Others are the result of thumb-sucking (thumb-sucking) in infancy. The prevention and treatment of nail biting fetish focuses on psychotherapy. It is important to adjust the child’s living environment and remove all kinds of stressful and worrying psychological factors. Punishment, ridicule, scolding and intimidation do not help to correct the behavior. The use of bitter, pungent and spicy agents on the nails and finger gloves can only temporarily suspend the behavior. Stimulation with substances and sedation are also not recommended. The child should be guided positively by explaining the reasons and dangers of nail biting. Children should be given educational games and toys to distract them. Children should be provided with a variety of after-school activities to encourage them to actively participate in beneficial group activities and normal social interactions. Early psychological treatment is recommended. The nails and epidermis of bites should be protected to prevent infection.