Longitudinal nail ridges can be caused by physiologic factors as well as pathologic factors such as malnutrition, chemical attack, skin lesions and endocrine diseases. The main feature of longitudinal ridge of nail is the appearance of line-like stripes of varying shades of color in the direction of the longitudinal axis of the nail, often with one or more stripes from the root to the end of the nail, and the nail plate can become thin and brittle, and the end of the nail is often ruptured or delaminated. 1. Physiologic longitudinal ridge of the nail: physiologic longitudinal ridge of the nail is mostly mild, and becomes more obvious with age. 2. Nutritional deficiencies: mainly due to the lack of vitamins and trace elements such as calcium and iron, resulting in malnutrition of the nails, leading to longitudinal ridge. 3. Chemical attack: long-term exposure to certain pigments, solvents and osmotic agents, such as alcohol, benzene, ketones and other chemical substances or nail polish containing these ingredients, can cause nail plate damage and lead to longitudinal ridge. 4. Skin lesions: lichen planus, chronic eczema, pemphigus and other skin lesions can violate the nails, can be secondary to longitudinal ridge. 5. Endocrine diseases: such as hypothyroidism caused by low calcium, can also cause longitudinal ridge. The causes of longitudinal ridge of the nail are more, when there is a more serious longitudinal ridge of the nail or nail plate thinning and brittle, it is recommended to go to the hospital in time to find out the cause of the disease, for targeted treatment.