Objective: To investigate the endoscopic and pathological characteristics of gastric adenomatous polyps and to assess the potential risk factors for canceration of gastric adenomatous polyps. Methods: The endoscopic and pathological characteristics of the patients with gastric adenomatous polyps from January 1, 2005 to December 31, 2019 were summarized retrospectively, and the risk factors of canceration were analyzed. Results: A total of 125 patients with gastric adenomatous polyps were included, 51.20% of whom were females. The average age was (66.7±12.3) years. 64.80% of patients with gastric adenomatous polyps equal or more than 65 years old, and only 5.60% of the patients less than 45 years old. Adenomatous polyps were mostly distributed in the corpus and antrum with 40.80% and 32.80%, respectively. The majority of them were single (90.40%) and sessile (76.81%). 65.4% of adenomatous polyps were no more than 1.0 cm in diameter, and 23.20% of patients with adenomatous polyps were combined with hyperplastic polyps and/or fundus glandular polyps, and 1.60% had both pathological types of polyps. 58.62% (17/29) patients with hyperplastic polyps and/or fundus glandular polyps had multiple polyps. 1.60% (2/125) of the patients had gastric neuroendocrine tumor of G1 stage. Synchronous gastric cancer was detected in 13.60% (17/125) of the patients with adenomatous polyps, and the proportion of low-grade intraepithelial neoplasia was 18.40% (23/125). The main types of synchronous gastric cancer were progressive (70.59%) and undifferentiated (66.67%). Chronic atrophic gastritis with intestinal metaplasia was found in 52.80% of the patients, and autoimmune gastritis accounted for 11.20%. The positive rate of Helicobacter pylori was 21.60%. The canceration rate of gastric adenomatous polyps was 20.80%. The cancer was mainly differentiated, but there was sigmoid ring cell carcinoma as well. Diameter of >1.0 cm (OR=5.092, 95%CI: 1.447-17.923, P=0.011), uneven surface morphology and erosion (OR=13.749, 95%CI: 1.072-176.339, P=0.044) were independent risk factors of adenomatous polyps. Conclusion: The synchronous gastric cancer is common and the canceration of gastric adenomatous polyps is high with diameter and surface morphology as independent risk factors. We should pay attention to the identification of the pathological types of polyps and the evaluation of the whole gastric mucosa during the endoscopic examination.