Basal cell carcinoma (BCC), also known as basal cell epithelial carcinoma, is a common form of facial malignancy. It is mainly composed of mesenchymal-dependent multipotent basal-like cells. Basal cell carcinoma is most common in middle-aged and elderly people, especially in exposed areas such as scalp, face and neck, and in outdoor workers, suggesting that the development may be related to sun exposure and ultraviolet light. Patients who have received radiotherapy for a long time are also prone to develop the disease in their skin. The incidence of basal cell carcinoma increases significantly with long-term intake of inorganic arsenic or drinking water or food with high arsenic content. The early manifestation of basal cell carcinoma is not obvious, but mostly appears as round patches with bright surface and elevated edges, with thin epidermis and often freckle-like small black spots. Some of them also have small and shallow vesicles, crusts or superficial ulcers, mostly without inflammatory reactions. Because of the inconspicuous characteristics, early stage often cannot attract attention and timely diagnosis. Later, there are four types according to the different biological characteristics of the manifestations: 1. nodular ulcer type: the center is a larger ulcer, the edge of the envelope is pearl-like. 2, pigmented type: similar in appearance to the nodular ulcer type, but the lesion is accompanied by increased pigmentation of dark brown color. 3.Sclerotic type: manifested as sclerotic yellow-white plaques with hard texture and indistinct borders, whose epidermis is intact for a long time. 4, superficial type: commonly found in the upper chest (more common in older women), the lesions are erythematous or desquamative patches, gradually expanding to the periphery; the patches may be partially surrounded by pearl-like edges, and small superficial ulcers and crusts are usually visible on the surface. The nodular ulcerative, pigmented, and sclerotic types are found on the face, and the superficial type is commonly found on the upper chest. The nodular ulcerated type and pigmented type are less invasive and can be confined to 4-5 mm of normal tissue around the lesion during excision or radiotherapy. The sclerotic type is more invasive and insensitive to radiotherapy, and surgical excision is limited to 1~1.5 cm of normal tissue around the lesion and deep to deep fascia. Of the above four types, the nodular ulcer type is the most common, and except for isolated cases, distant metastasis does not usually occur (the chance of metastasis is about 1 in 1,000). Treatment: Surgical extended excision therapy is preferred. Emphasis is placed on complete resection, and intraoperative rapid cryopathological examination is required to exclude tumor cell remnants at the cut edge if available. Secondly, radiotherapy can be considered for patients who cannot tolerate surgery and whose staging is not sclerotic. Other treatments such as liquid nitrogen therapy and laser therapy have a higher recurrence rate, and the exact degree of treatment effect is not as good as surgical resection, so surgery is still the first choice. Chemotherapy is rarely used as a treatment for this disease.