Both pigmented nevi and melanomas originate from melanocytes. Most common nevi do not develop into malignant tumors, and only a few pigmented nevi, especially giant congenital pigmented nevi, have the possibility of malignant transformation. Therefore, there is no need to “talk about moles”, as the incidence of melanoma is very low in China, and the most common sites in the Chinese Han population are the hands and feet. The color and shape of moles should be taken seriously when they change. There are two types of pigmented moles: congenital and acquired. Among them, acquired nevi are formed by nesting nevus melanocytes, which can appear in various parts of the human body, and the most common locations are parts that are often exposed to sunlight, such as face, scalp, and limbs. Mole is a benign skin tumor and usually will not become malignant But when the color of pigmented mole changes and is uneven; the boundary of mole changes from regular to irregular; lesions appear asymmetrical; and without trauma, mole breaks out with bleeding, we should go to regular hospital in time to exclude the possibility of melanoma. In addition, whether a pigmented mole is malignant or not is not directly related to its flat or raised form on the skin, and there is no correlation with whether hair grows on the mole or not. The occurrence of melanoma is related to excessive sun exposure There are four main types of melanoma: the first type is malignant freckle nevus-like melanoma, which mainly occurs on the face, head and neck, and is more common in Westerners. The second type is the superficial spreading type, which often occurs on the trunk and lower legs. The third type is the nodule-like type, which is a late manifestation of melanoma. The fourth type is the limbic type, which occurs in the hands and feet, and is the most common type in Chinese people. The factors influencing the occurrence of melanoma are mainly related to race. Caucasians have significantly less melanin in their skin than blacks or yellows, and have a relatively weaker ability to resist ultraviolet light, resulting in a higher incidence of melanoma. Secondly, environmental factors, where the skin is exposed to sunlight for a long time, increase the chance of melanoma. Finally, viral infection and radiation may have a relationship with the occurrence of melanoma. In conclusion, melanoma can come from malignant transformation of pigmented nevi or occur directly on the skin. Avoiding prolonged exposure of bare skin to sunlight and avoiding trauma to the skin area are currently known ways we can prevent the occurrence of melanoma. As with other tumors, melanoma is diagnosed by histopathological sections, and once melanoma is highly suspected, pathological examination is necessary.