The appearance of two layers on the nail cover may be caused by the lack of calcium, phosphorus and other trace elements, or trauma, fungal infection and other reasons. If there is congenital malnutrition and excessive picky eating or partiality, it will cause insufficient nutrient intake into the body, resulting in a lack of calcium, phosphorus and other elements, which will lead to significant changes in the cuticle, resulting in layering of nails. If the nail is accidentally hit by a heavy object falling or trauma caused by other factors, it may also cause the nail to appear two layers. If there is a fungal infection in the nail, it may cause the nail to appear thickened, cloudy, discolored, etc., and in severe cases, the nail may even be separated, the surface is rough and other symptoms, the nail becomes two layers may be due to a fungal infection caused by. Nail cover two layers may also be caused by other reasons, it is recommended to go to the hospital in a timely manner, clear causes under the guidance of the doctor to treat the symptoms.