Objective To evaluate the clinical efficacy of endoscopic treatment for early nonampullary duodenal cancer. Methods Data of patients with early nonampullary duodenal cancer, who underwent endoscopic treatment from January 2015 to January 2021 at Beijing Friendship Hospital were retrospectively analyzed. Baseline data, endoscopic treatment methods, wound closure, pathology, the occurrence and outcome of complications of patients were studied. Results A total of 47 patients who successfully went through endoscopic treatment were enrolled. Seventeen cases received endoscopic mucosal resection (EMR), 5 cases received endoscopic submucosal dissection (ESD), and 7 cases received ESD+EMR (hybrid ESD). Six cases were converted to hybrid ESD due to difficulty in ESD. Four cases received full-thickness resection with over-the-scope clip system (OTSC), and 8 cases received endoscopic piecemeal mucosal resection (EPMR). Among the 47 cases of early cancer, the en bloc resection rate was 83.0% (39/47), and the complete resection rate was 85.1% (40/47). Four patients (8.5%) had perforation which occurred at the duodenal descending part during the perioperative period, among whom, 2 patients (4.3%) recovered after endoscopic treatment, 2 others (4.3%) recovered after surgical intervention. There were no complications such as postoperative bleeding or infection during the perioperative period. Conclusion Endoscopic treatment for early nonampullary duodenal cancer is safe and effective. A specific treatment plan can be selected according to the location, size and specific conditions of the lesion. For the operation of the descending part, it is necessary to be more vigilant to against the occurrence of perforation complications.