Objective To evaluate the clinical efficacy of endoscopic treatment of superficial non-ampullary duodenal adenoma. Methods A retrospective analysis was performed on the clinical data and follow-up information of patients diagnosed with superficial duodenal non-ampullary adenomas via preoperative endoscopy and treated endoscopically at Peking University First Hospital between January 2013 and January 2024. The overall en bloc resection rate, complete resection rate of the lesion, perioperative complications, and recurrence rates were evaluated. Patients were categorized into three groups based on their treatment modality: endoscopic mucosal resection (EMR) （n=46）, endoscopic submucosal dissection (ESD) （n=16）, and modified ESD (ESD with snare, ESD-S) （n=24）. Comparative analyses were conducted to evaluate operative time, en bloc resection rate, and complete resection rate among the three groups. Results Among 86 patients, the overall en bloc and complete resection rates were 87.2% (75/86) and 86.0% (74/86), respectively. No case of delayed bleeding was observed during the perioperative period. Intraoperative perforation occurred in two patients, both of whom improved following conservative management. Delayed perforation was noted in four patients, and three of them were successfully managed with surgical intervention, while one case was resolved after conservative treatment. During the follow-up period, local recurrence was identified in two patients. Following re-treatment with endoscopy and continuous surveillance, no further recurrence was observed. The operative times for the EMR group, ESD-S group, and ESD group were 4 (1-36) minutes, 25 (5-190) minutes, and 46 (5-150) minutes, respectively. Significant differences were observed in operative times among the three groups (Hc=49.892, P<0.001). The en bloc resection rates for the EMR, ESD-S, and ESD groups were 80.4% (37/46), 91.7% (22/24), and 100.0% (16/16), respectively. The complete resection rates were 80.4% (37/46), 91.7% (22/24), and 93.8% (15/16) for the respective groups. Conclusion Endoscopic treatment demonstrates favorable efficacy and safety for superficial non-ampullary duodenal adenoma. In addition to traditional EMR and ESD, ESD-S is also an effective procedure for endoscopic treatment of non-ampullary duodenal adenoma.