Clinical characteristics and diagnostic typing of scar cancer: skin scar cancer is a malignant tumor that occurs in skin scar tissue. Any skin injury caused by any reason can leave a scar, and the repeated ulceration and persistence of scar is the main cause of scar cancer, which is most common in clinical practice after burns. The development characteristics of scar cancer are: 1. There is often a long history of skin ulcers or unstable scar formation. 2. Unstable scar is prone to break down and erode due to itching, touch, friction and pressure, etc. If the erosion surface is not treated properly, the ulcer surface may persist, and long-term chronic inflammatory stimulation may eventually cause the ulcer to become malignant and form an erosive ulcer or cauliflower-like lesion. Generally speaking, it is not very difficult to diagnose scar cancer based on medical history and clinical manifestations. Scar cancer is divided into acute and chronic according to the duration of scar cancer, and those with the interval between scar formation and cancer occurrence within 1 year are called acute scar cancer, while those with more than 1 year are called chronic scar cancer. However, the diagnosis of scar cancer is still not very uniform in terms of typing. In terms of pathological typing, squamous cell carcinoma and basal cell carcinoma were the majority, with 9 cases (81.8%) of squamous carcinoma and 2 cases (18.2%) of basal cell carcinoma diagnosed, while no other types were found. In terms of clinical typing, the author concluded through clinical observation of 11 cases of scar carcinoma and literature review that squamous carcinoma and basal cell carcinoma behave differently. Squamous carcinoma mainly appears as ulcerative, cauliflower, bulging and mixed types, while basal cell carcinoma mainly appears as pigmented, sclerotic, nodular ulcerative, superficial and fibroepithelial tumor types. Treatment and prevention of scar carcinoma: Once diagnosed, surgery is the key and best method for skin scar carcinoma because of its slow development and late metastasis. All 11 patients in our group underwent surgical enlarged excision + flap or (and) skin graft repair after local tissue biopsy to confirm the diagnosis of scar cancer. Third, scar cancer can be prevented. Most of the scar is a relatively long process from ulcer formation to cancer. From this group of 11 patients, it can be found that: the short one is 1 year and the long one is 60 years. The main factors for the final occurrence of cancer are as follows: 1. economic difficulties, scar ulcers are not treated for a long time. 2.Insufficient understanding and attention to scar ulcers, and let them go. 3.Lack of professional knowledge about the cancer of scar ulcer. In order to achieve the purpose of preventing scar cancer, it is necessary to take the following measures: 1. Cure various burns and traumas by regular methods to prevent the formation of unstable scar; 2. Take active measures such as cosmetic surgery or use drugs such as oral cumene tablets and various scar softening creams to make the scar not itchy and soften to prevent the occurrence of ulcers; 3. 4. In recent years, with the continuous improvement of grassroots medical conditions, the establishment and improvement of new rural cooperative medical system and urban residents’ basic medical insurance system, people have the conditions to seek medical treatment in formal hospitals. Therefore, popularizing professional knowledge about scar, ulcer and cancer among the public is also an important way to prevent and treat scar cancer.