Any lesion suspected of malignant melanoma must be promptly excised or biopsied to determine the histological diagnosis. Excisional biopsy is not easy to cause injury and tumor cell spread, and it is convenient to perform stratified sectioning and determine the depth of tumor infiltration, which is extremely important for estimating regional lymph node metastasis and prognosis. If the tumor is too large for excisional biopsy, excisional biopsy or puncture biopsy can be performed. For those who suspect malignant melanoma, the lesion should be excised together with the surrounding 0.5~1.0 cm of normal skin and subcutaneous fat and then do pathological examination. Generally, excision or biopsy is not performed unless the lesion has already formed an ulcer or the lesion is too large to cause disfigurement or disability in one excision and must be confirmed by pathology first, but the excision biopsy must be done as close as possible to the radical surgery. In a prospective analysis, the WHO Collaborating Centre for the Evaluation of Malignant Melanoma Treatment concluded that excisional biopsy has no impact on prognosis, and that excisional biopsy provides insight into the depth and extent of infiltration of the lesion and facilitates the development of a more rational and appropriate surgical plan. Extensive excision of the primary lesion should remove the normal skin 3.0-5.0 cm from the tumor margin, including the satellite nodes around the tumor to the depth of subcutaneous adipose tissue and reaching the muscle membrane. If local lymph node enlargement is felt clinically, lymph node dissection should be performed. For patients who cannot feel local enlarged lymph nodes clinically, about 20% of them have tumor metastasis under microscope, and lymph node dissection is also advocated; cases of metastasis after radical surgery are not uncommon, therefore, postoperative adjuvant treatment is needed, and malignant melanoma located at the extremity often requires finger (toe) amputation.