Layering of the nail cap may be caused by physiological factors such as frequent manicures and long-term exposure to chemical detergents, or it may be due to diseases such as onychomycosis and lichen planus. 1. Physiological factors: if patients often use nail polish, or long-term need to contact with chemical detergents, may increase the brittleness of the nails, which will appear in the case of delamination of the nail cover. 2. Onychomycosis: it is mainly a nail lesion caused by dermatophytes invading the nail plate and the nail underneath, and the patient mainly manifests the symptoms of cloudy nail plate, separation and buckling. 3. Lichen planus: the cause of the disease is not clear, mostly related to immunity, heredity, infection and other factors. Patients will appear nail plate thinning, longitudinal crack, nail layering and other phenomena. There are many reasons that lead to nail cover layering, after excluding physiological factors, patients are advised to go to the hospital to clarify the cause of the disease.