Melanoma is more likely to occur between the ages of 30-60. Especially in older patients, the younger ones generally have less malignancy. The prognosis is better after early surgical excision. Melanoma is more malignant and has a high likelihood of recurrence. How to prevent melanoma and detect early signs of melanoma is the key to prevent melanoma. How to prevent melanoma should be done as follows: a. For pigmented nevi that occur in easy to rub parts, biopsy should be taken. For example, children with large hairy nevi in the waist, which are often rubbed and squeezed by the belt, should have all of them removed as early as possible. If it is difficult to remove all of them at one time, the main part of the mole can be removed in the middle of the mole before malignant transformation, and the skin around the mole can be sutured on both sides, and then the rest of the mole can be removed until all of the mole is removed to prevent malignant transformation. Each specimen must be sent for pathological examination. If there is malignant change, all the specimens should be excised and implantation should be performed. Second, it is not advisable to stimulate the nevus with corrosive drugs or thorough freezing. It is dangerous to repeatedly freeze the nevus several times because it often becomes malignant due to traumatic stimulation. Some people have had malignant changes due to incomplete freezing at one time. About 30-50% of malignant melanomas are related to external irritation. It is safer and more reliable to remove the mole at one time if it is needed for cosmetic reasons. The combination of freezing and excision should be done at one time, never in parts, and the excised specimen should be sent for pathological examination.