There are three main methods to examine the stomach: upper gastrointestinal barium meal examination, CT examination, and gastroscopy. The upper gastrointestinal barium meal examination can roughly observe the shape and outline of the stomach and check whether there are ulcers, tumors, polyps and other lesions. CT examination has a higher detection rate of gastric diseases than barium meal examination, and it can calculate the size of gastric lesions, blood supply and the relationship with surrounding organs, which is especially important in the preoperative staging of gastric cancer patients. CT can be used for preoperative staging of gastric cancer, thus guiding patients with gastric cancer to adopt reasonable treatment methods. Gastroscopy is the most widely used examination, which can visually observe the lesions of gastric mucosa and take pictures of them, and after the lesions are found, pathology can be taken for clear diagnosis. The advantages of gastroscopy are high detection rate and simple operation; the disadvantage of gastroscopy is that during the process of gastroscopy, patients can have nausea, vomiting and other discomfort.