For typical gastric cancer, the diagnosis can be made under gastroscopy, and the diagnosis of gastric cancer mainly relies on electronic gastroscopy and pathological examination. Normal electrogastroscopy can clarify most gastric cancers, such as ulcerative type, and lesions with obvious nodular hyperplasia. For some small lesions or lesions with less obvious differentiation, which cannot be judged empirically, it is necessary to wait for pathological results. For gastric cancer similar to leathery stomach, the pathology cannot be clarified at the first time, and even some patients need multiple pathological examinations to be clarified, and very few patients can be diagnosed clearly only after post-surgery sending for examination. If a patient finds a swelling growth in gastroscopy, the microscopic diagnosis of gastric cancer is highly suspected, but the diagnosis cannot be fully confirmed, for example, there is erosion on the surface of the swelling with untidy edges, stained, bleeding and uneven base of the ulcer, as well as grayish color and poor demarcation with surrounding mucosa, even the stomach wall is relatively stiff, gastric peristalsis is slowed down or disappeared, and the stomach wall is thickened, etc. All these manifestations can be highly suspected of gastric cancer under the microscope. However, it is necessary to take mucosal biopsy from the lesion area for pathological confirmation under gastroscopy in order to confirm the diagnosis of gastric cancer 100%.