Malignant melanoma is a highly malignant skin tumor. It is common in Caucasians and rare in Yellows. The incidence rate in China is about 1 in 100,000. It often occurs in the hands and feet, mostly from the development of the original nevus, and a few from the malignant transformation of long-standing wounds. The manifestation of nevus malignant change: nevus discoloration, irregular edge, enlargement, rupture, and small satellite nevus appear around. If malignancy is suspected, go to dermatology or bone and soft tissue tumor department for examination in time. If necessary, biopsy should be done to clarify the diagnosis. After the diagnosis is confirmed, it must be treated in a specialist. For stage 1 and 2, surgery is almost curable, for stage 3, isolated thermal perfusion chemotherapy of the limb is effective, and biological treatment for stage 3 and 4 is effective. Chemotherapy has a role, and radiotherapy is used for patients who are not sensitive to other methods. Originally not a very serious disease, once repeated delays and misdiagnosis, non-standardized treatment, how many tragic consequences. Stage 3 amputation is useless, how many people have had their limbs amputated for nothing, and it is not uncommon to see one amputation after another. The key is: more attention, early detection, early treatment, standardized treatment.