Endoscopic submucosal dissection (ESD) is a new treatment tool that has emerged in recent years. With minimally invasive techniques, endoscopic resection of large mucosal lesions of the digestive tract can be accomplished while “sweeping” some of the submucosal lesions to achieve radical treatment of tumors. The procedure is divided into marking, submucosal injection, margin dissection, peeling and wound treatment. Indications: (1) Giant flat polyps in GI tract: polyp with diameter less than 2CM is usually removed by endoscopic mucosal resection (EMR); polyp with diameter greater than or equal to 2CM is recommended to be treated by ESD, and the lesion is completely removed in one time. (2) Early stage cancer: according to the experience of the operator, combined with staining endoscopy, magnification endoscopy and ultrasonic endoscopy, the scope and depth of infiltration of early stage cancer can be determined, and ESD treatment can achieve the same radical effect as surgery for early stage cancer confined to the mucosal layer and without lymph node metastasis in the submucosal layer. (3) Submucosal tumors: Tumors originating from the myxomucosal layer and submucosal layer can be identified by ultrasound endoscopy, and the lesions can be completely peeled off by ESD treatment. Advantages: (1) Compared with traditional surgical methods, endoscopy has the advantage of being less invasive, fully reflecting the superiority of minimally invasive treatment; patients do not need caesarean operation, less hospitalization days, and lower surgical cost than traditional surgery. In terms of efficacy, the postoperative tumor recurrence rate of patients who underwent ESD surgery is about 0.6%, which is basically the same as that of traditional open surgery. (2) Endoscopic resection has the advantage of obtaining complete pathological specimens, which is helpful for clarifying the degree of tumor infiltration, differentiation, vascular and lymphatic infiltration, assessing patient prognosis, and deciding whether additional surgical procedures are needed. The basic requirement for endoscopic resection of lesions is complete resection with no residual lesions. (3) Individualized and targeted, ESD treatment can be tailored to the site, size, shape and tissue type of EGC to ensure complete resection of the tumor while maximizing the preservation of normal tissue and its function. (4) It is less invasive and easily tolerated by patients. (5) The same patient can receive multiple ESD treatments, and multiple sites can be treated at the same time. (6) Compared with EMR, ESD can remove large, irregular or combined ulcerated and scarred tumors from the intrinsic muscular surface in one go, and the one-time complete resection rate is over 96%, which obviously reduces the residual tumor and recurrence.