Objective To summarize the clinical characteristics of bleeding during endoscopic submucosal dissection (ESD) and to analyze the risk factors for bleeding. Methods Data of patients who received gastric ESD in endoscopy center of Peking Union Medical College Hospital from January 2015 to December 2019 were reviewed. The medical history, characteristics of gastric lesions, operation process and prognosis of the patients were analyzed. Results A total of 437 gastric lesions of 422 patients were included in this study, and 406 lesions were gastric epithelial tumors. The bleeding rate during ESD was 32.3% (141/437), including 2 cases of acute massive hemorrhage. Intraoperative hemorrhage during ESD increased the incidence of myometrial injury and intraoperative perforation, and prolonged the operation time. Multivariate regression analysis showed that risk factors for bleeding during ESD were anatomical adhesion, the lesion location in the upper and middle 2/3 of the stomach, the lesion area ≥ 15 cm2, male, and non-ESD absolute indications. Conclusion Bleeding is the speed limiting factor for gastric ESD. For male patients, when the lesion is located in the upper and middle 2/3 of the stomach, large with anatomical adhesion during operation, precaution should be taken for intraoperative hemorrhage.