Abstract: OBJECTIVE To investigate the epidemiological characteristics of peptic ulcers and the nosocomial infection after digestive endoscopy. METHODS A total of 1912 patients with peptic ulcers who were admitted to Qinghai Provincial People's Hospital and Qinghai Red Cross Hospital and underwent digestive endoscopy from Jan. 2024 to Jan. 2025 were selected as the research objects. They were divided into the infection group with 114 cases and the non-infection group with 1798 cases. The epidemiological characteristics of patients with peptic ulcers were described, the risk factors of nosocomial infection after digestive endoscopy were analyzed, and the infection site and pathogenic bacteria distribution of the infection group were statistically evaluated. RESULTS The male-to-female ratio in peptic ulcer patients was about 2.07∶1. Patients aged 40 to 60 accounted for 52.04%, the highest. Patients in Helicobacter pylori(Hp) infection represented 65.12%. Peptic ulcers were more likely to develop in spring (31.28%) and winter (27.04%). Multivariate analysis showed that other invasive procedures, use of immunosuppressants, bleeding ulcers, long hospital stay, and prolonged duration of endoscopy were risk factors for health care-associated infection in the peptic ulcer patients after digestive endoscopy (P＜0.05). In the infection group, the patients with respiratory system infections accounted for 47.37%, the patients with gastrointestinal tract infections 27.19%. Totally 114 strains of pathogenic bacteria were detected, including gram-negative bacteria (71 strains, 62.28%). CONCLUSIONS Peptic ulcers are more common in males, population aged 40 between 60 years old, and population with high positive rate of Hp infection and are highly prevalent in spring and winter. Health care-associated infections after digestive endoscopy are associated with other invasive procedures, use of immunosuppressants, bleeding ulcers, long length of hospital stay, and prolonged duration of endoscopy. The patients with respiratory system infections and the patients with gram-negative bacteria infections are dominant among the patients with health care-associated infections.