As we all know, the five-year survival rate of early gastric cancer is 90%, while the five-year survival rate of progressive gastric cancer is only 30%, and this 30% of survival has to endure the pain of surgery and chemotherapy. Therefore, early detection of gastric cancer is very important, and if it can be detected and treated early, it can be said that gastric cancer is a curable disease and can be cured by minimally invasive endoscopic treatment. The reality is that the rate of early gastric cancer surgery in our country is only 10%, compared with 70% in Japan and 50% in Korea. This 10% vs. 70% figure is very embarrassing for Chinese endoscopists. Therefore, only early detection and early treatment can reduce the mortality rate of gastric cancer. To diagnose early gastric cancer, we should pay attention to the following six aspects. 1. Raise the vigilance and awareness of gastric cancer. Nearly half of early gastric cancer patients have no clinical symptoms, and only some of them have mild indigestion and other symptoms, such as hidden pain and discomfort in upper abdomen, slight fullness, pain, nausea and belching. Most of the patients are already in the middle and late stages when they are diagnosed, because there are common misunderstandings about gastric cancer. For example, when they have symptoms such as slight obstruction in eating, epigastric pain and loss of appetite, they do not go to hospital and casually take commercially available gastric drugs; when they face symptoms such as unexplained wasting and weakness, they often think that they are caused by work fatigue and mental stress. All these situations cause the condition cannot be diagnosed early. Therefore, middle-aged and elderly people must be alert once they have epigastric pain, abdominal distension, wasting and difficulty in swallowing. 2.Check and treat precancerous lesions. The World Health Organization has classified chronic atrophic gastritis, intestinal epithelial hyperplasia, atypical hyperplasia of gastric mucosa, gastric ulcer, gastric polyp, and patients with benign gastric diseases after major gastrectomy as pre-cancerous lesions of the stomach. Those with H. pylori infection (the risk of gastric cancer is 3-6 times higher in those with positive H. pylori infection than in those with negative infection) should be examined and treated regularly. 3.Gastroscopy. Gastroscopy should be the first choice for early gastric cancer diagnosis. For cases suspected of ulcer, gastric mucosal heterogeneous hyperplasia or gastric cancer, taking biopsy can quickly obtain the basis for early pathological diagnosis. 4.Imaging, X-ray gas-barium double contrast imaging is also a method to detect lesions at an early stage, but in order to confirm the diagnosis, gastroscopy and biopsy should still be mobilized to obtain the diagnosis of pathology. 5.Ultrasound endoscopy. Now there is a new gastroscope that can be installed with ultrasonic probe, which can obtain early diagnosis of gastric bulging lesions such as submucosal or extra-mucosal tumors, and can clearly show the structure of each layer of gastric wall and the depth of tumor invasion. 6. Patients with suspicion must be tracked and observed and reviewed once in 1 to 3 months.