Gastric cancer is one of the malignant tumors that threaten human health, and its incidence and mortality rate remain high. Early detection, early diagnosis and early treatment are still the main means to increase the cure rate and improve the prognosis. Its initiation is a multi-gene and multi-stage process with geographical characteristics, and the causes of its development are related to multiple factors, such as: environment and diet, living habits, bacterial infection, genetic mutation, long-term chronic inflammation, hyperplasia, etc. The main things that need early detection and treatment are some precancerous lesions and diseases, such as: chronic atrophic gastritis, gastric ulcer, intraepithelial neoplasia, polyps, etc. People need to pay attention to the following points: 1. middle-aged patients, especially men, 40 years old upwards, with recent epigastric discomfort or pain irregularities; 2. unexplained wasting, weakness and loss of appetite; 3. black stools and vomiting blood; 4. heterogeneous hyperplasia has been found under gastroscopy; 5. a history of ulcers for many years, long-term untreated or recurrent or recent severe and irregular symptoms. Patients who present with several points of appeal should seek prompt medical attention.