Fingernail vertical lines usually indicate malnutrition, onychomycosis, onychomatous nevus and so on. 1. malnutrition: the growth of finger nails is related to calcium, protein, vitamin D and other nutrients, the lack of these nutrients will lead to poor nail development, some vertical lines may appear. 2. Ringworm of the nail: when the finger is invaded by fungus after trauma, it will cause ringworm of the nail, which will make the nail plate discolored, brittle and turbid, and there will be the appearance of vertical lines. 3. Onychomycosis: it is a kind of abnormal nevus, which manifests itself as a dark colored rash in the form of strips, and it is easier to be found in the crowd. If it doesn’t change for a long time, it can’t be dealt with in any way, but if the color becomes darker, the area becomes bigger and other changes happen in a short time, it is necessary to consult the doctor in time. Vertical lines on the fingernail should not be ignored, and it is recommended to go to a regular hospital for timely treatment.