Objective To study the effectiveness of a strategy for detecting early gastric cancer using high-definition gastroscopy. Methods A total of 849 patients over 35 years old who underwent gastroscopy in the Seventh Medical Center of PLA General Hospital from December 2018 to January 2019 were enrolled to a prospective study. During gastroscopy, biopsies were taken at any suspicious lesions in patients who had never been infected with Helicobacter pylori. In ulcer-type lesions, biopsies were taken at the edge of the ulcer. Outside the atrophic area, biopsies were taken at lesions in the cardia which were reddish under white light, or lesions in the non-cardiac area which were white or showed clear borders under white light. Inside the atrophic area, biopsies were taken at elevated lesions with clear borders or irregular depressions on the top, or flat/depressed lesions with irregular borders or being ocherous under narrow band imaging. In addition, biopsies were performed on any lesion that did not meet the above standard but was considered necessary. The high-risk patients were followed up by gastroscopy to observe the detection and missed diagnosis of neoplasm that meet the above standard, and to determine the sensitivity and positive predictive value of the strategy. Results A total of 548 patients were biopsied (781 lesions). Among the 327 lesions that met the above standard, 16 lesions (4.9%) were diagnosed as epithelial neoplasm, of which 10 (3.1%) were high-grade neoplasm. Among the 454 lesions that did not meet the standard, only 1 (0.2%) epithelial neoplasm was diagnosed, and there was no high-grade neoplasm. The positive predictive value of this screening strategy for gastric epithelial neoplasm and high-grade neoplasm was higher than those who did not meet the standard (4.9% VS 0.2%, χ2=19.49, P<0.01; 3.1% VS 0, P<0.001). There were 146 patients (17.2%, 146/849) followed up by gastroscopy. During the follow-up, 2 high-grade intramucosal neoplasms were found. 84.2% (16/19) of epithelial tumors and 83.3% (10/12) of high-grade neoplasm were detected during the initial gastroscopy. Conclusion This screening strategy can efficiently detect early gastric cancer under high-definition gastroscopy.