Endoscopic submucosal dissection is a new treatment tool that has emerged in recent years. With the minimally invasive technique, ESD can remove a large and complete lesion and “clean” part of the submucosal lesion at the same time to achieve the effect of radical treatment of the tumor. The procedure is divided into marking, submucosal injection, margin dissection, dissection and wound treatment. I. Indications for ESD: 1. Huge flat polyps in the digestive tract. Polyp with diameter less than 2CM is usually removed by endoscopic mucosal resection; ECD treatment is recommended for polyps with diameter greater than or equal to 2CM, with 1 complete excision of the lesion. 2.Early stage cancer. According to the operator’s experience, combined with staining endoscopy, magnifying endoscopy and ultrasonic endoscopy, the infiltration range and depth of early cancer can be determined. For early cancer of submucosal layer confined to mucosal layer and without lymph node metastasis, ESD treatment can achieve the same radical effect as surgery. 3.Submucosal tumor. Tumors originating from the muscularis mucosa and submucosa layer can be identified by ultrasonic endoscopy, and the lesions can be completely peeled off by ESD treatment. Advantages of ESD: 1. Compared with traditional surgical methods, endoscopy has the advantage of small invasion, fully reflecting the superiority of minimally invasive treatment; patients do not need to undergo caesarean section, less hospitalization days, and lower surgical cost than traditional surgery. In terms of efficacy, the postoperative tumor recurrence rate of patients undergoing 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 to clarify the degree of tumor infiltration, differentiation, vascular and lymphatic infiltration, assess the patient’s prognosis, and decide whether additional surgical procedures are needed. The basic requirement for endoscopic resection of lesions is complete resection without residual lesions. ESD treatment can be individualized according to the location, size, shape and tissue type of EGC, which can ensure complete resection of the tumor while maximizing the preservation of normal tissues and their functions. 4.Small trauma, easily tolerated by patients. 5.The same patient can receive several times of ESD treatment, and at the same time, multiple sites can be treated at one time. 6.Compared with EMR, ESD can completely peel off the tumor with larger area, irregular shape or combined with ulcer or scar from the intrinsic muscle surface at one time, and the one-time complete resection rate reaches more than 96%, which obviously reduces the residual tumor and recurrence. The development of ESD has enabled the effective treatment of huge flat polyps, early carcinoma and submucosal tumors in the digestive tract, with less trauma, shorter hospital stay, lower cost, better patient tolerance, ideal treatment effect and significantly improved quality of life, fully reflecting the superiority of “minimally invasive treatment”. It has greatly improved the detection rate and endoscopic treatment level of early cancer and submucosal tumor in the gastrointestinal tract, and has become a development trend with broad application prospects. Endoscopic ESD treatment of ectopic pancreas