Buccal mucosal carcinoma is a cancerous lesion originating from the buccal mucosa. According to the TNM classification and staging of the International Union Against Cancer UICC, the anatomical boundaries of buccal mucosa are: the anterior boundary is the medial mucosal line of the inner lip, the posterior boundary is the front of the pterygomandibular ligament, and the upper and lower boundaries are the gingival-buccal sulcus. More than 90% of buccal cancer is squamous carcinoma, and 5%-10% is epithelial carcinoma of glandular origin. When the cancer invades deep tissues such as muscle or combined with infection, it will appear obvious pain, accompanied by different degrees of mouth opening limitation until the teeth are closed. Toothache or tooth loosening, secondary bleeding, etc. may occur. It has the characteristics of infiltrative growth and high local recurrence rate. Clinical manifestation and diagnosis: Buccal mucosal carcinoma is mostly of ulcerative type, with infiltration in the base and surrounding area. There is no obvious symptom in the early stage, but when the lesion continues to develop or secondary infection occurs, there may be mild to moderate pain. When the buccal muscle and masticatory muscle are invaded, mouth opening may be restricted and gradually aggravated. In advanced stage, the cancer may penetrate the skin of buccal area to form sinus tract; invade the upper and lower gums and jawbone, causing toothache, tooth loosening and jawbone destruction; it may spread to soft palate, lateral wall of pharynx and pterygomandibular ligament laterally. The rate of cervical lymphatic metastasis of buccal mucosa cancer is high, ranging from 30% to 50% as reported in the literature. The submandibular lymph nodes are most frequently involved, followed by the deep superior cervical lymph nodes. Treatment: Comprehensive treatment mainly based on surgery, early superficial buccal mucosa cancer can be considered as radiation therapy alone. If the primary lesion of buccal cancer is less than 1cm in diameter and superficial, it can be locally enlarged and the remaining trauma can be stretched and sutured or transplanted with free skin pieces. If the lesion diameter is larger than 1 cm and the infiltration depth reaches the muscle layer, the buccal fat pad, frontal flap, temporal muscle flap, temporoparietal fascial flap, cervical flap, thoracic triangle flap and forearm flap can be used for repair after local enlargement resection. If buccal cancer invades the jaw bone, the scope of jaw bone resection should be designed according to the principles of tumor surgery depending on the size of tumor invasion. If the cervical lymph nodes are enlarged, therapeutic cervical lymphatic dissection should be performed. In principle, selective cervical lymphatic dissection should be performed for those who do not have enlarged lymph nodes on clinical examination, but the tumor thickness is 3.0mm or more or the primary foci are T2 or more. In intermediate and advanced cases, postoperative chemotherapy or radiation therapy should be supplemented.