Nevus is a pigmented nevus. Pigmented nevus can be removed by drugs with exfoliating properties, but it is not recommended to be applied in clinic nowadays because it is easy to form scar. Nevus pigmentosus is a benign tumor of melanocytes, located in the superficial part of dermis, its substance is nevus cells, and its interstitium is blood vessels, lymphatic vessels and connective tissues. The size of nevus is from the tip of a needle to the size of a coin, the hardness is the same as normal skin, the color is usually yellow, brown or black, but it can also be blue, purple or unpigmented. They can be removed by medication, laser or surgery. In the past, there was a method of using acidic or alkaline drugs to apply on the pigmented nevus, causing local chemical burns to get rid of the pigmented nevus, but it has been discarded by the clinic due to the fact that the degree of damage is not easy to control, and it is prone to cause damage to the normal tissues, with a higher possibility of infection and scar in the later stage. It is recommended that patients who are willing to have nevus treatment should go to regular medical institutions for consultation and standardized treatment so as to avoid adverse consequences.