Malignant melanoma is highly malignant, prone to early lymph node and hematogenous metastasis, and insensitive to adjuvant therapy such as radiotherapy and chemotherapy, with a poor prognosis. An important factor affecting its prognosis is whether local lymph nodes have metastasized. Approximately 20% of patients have metastasis before the appearance of local lymph node enlargement. For this group of patients, it is not yet possible to determine whether metastasis has occurred based on the available imaging methods. Therefore, there is still a great controversy as to whether lymph node dissection should be performed for early malignant melanoma. If one waits for observation and waits until clinical symptoms of lymph node enlargement appear before performing surgery, it will inevitably delay the condition of some patients; if all perform lymph node dissection surgery early, it will make most patients without metastasis undergo unnecessary surgery. Lymph node dissection may cause comorbidities such as limb edema, lymphatic leakage, limb pain and numbness, and the incidence is high, causing pain and inconvenience to patients’ life. Sentinel lymph nodes are the first station lymph nodes to which cancer cells are drained along the lymphatic vessels after they are shed from the primary tumor. Since it is the first lymph node receiving tumor drainage, it is the first to reflect the metastasis of tumor, so it is the most valuable lymph node for histological examination. The significance of sentinel lymph node biopsy is that the need for extensive regional lymph node dissection can be decided based on its pathological findings. Currently, sentinel lymph node biopsy has been used very commonly in Europe and the United States, and is a routine tool for the diagnosis and treatment of malignant melanoma. However, because the incidence of malignant melanoma in China is much lower than that in western countries, it is rarely performed and the operation is very irregular. In fact, the operation process of sentinel lymph node biopsy is very simple, especially the radionuclide labeling method, and the detection rate and accuracy are very high as long as the law of imaging is mastered; moreover, the biopsy surgery is very little damaged and can be performed simultaneously with the surgery of the primary lesion without adding additional pain to the patient.