Early detection, early diagnosis and early treatment are important for any disease, and the problem nowadays is that it is difficult to detect early. Besides caring more about the changes of one’s body, regular examination is essential. Clinical manifestations: 1. Stomach pain: it is the most common symptom of gastric cancer, which appears earlier; it is often manifested as upper abdominal discomfort in early stage and often misdiagnosed as gastroduodenal ulcer. 2.Loss of appetite, emaciation and weakness: this symptom can appear in the early stage and may not be accompanied by symptoms of gastric pain. Many patients often have complaints of weight loss at the time of consultation, and cachexia may appear in the late stage. Nausea and vomiting: This symptom is often caused by tumor-induced obstruction or gastric dysfunction. 4.Bleeding and black stool: In case of small amount of bleeding, there is only positive fecal occult blood (occult blood), but in case of larger amount of bleeding, there can be vomiting blood and black stool, which leads to decrease of hemoglobin, and then leads to different degrees of anemia. Some patients present with this as their main complaint. 5. Other symptoms: some patients may have diarrhea or constipation, lower abdominal discomfort, enlarged supraclavicular lymph nodes, ascites, jaundice, abdominal masses, ovarian masses, masses in the anterior rectal recess or anemia, emaciation, malnutrition or even cachexia. Diagnosis: Due to the lack of specific symptoms of early gastric cancer and the lack of effective and convenient screening means, the early diagnosis rate of gastric cancer in China is less than 10% at present. In order to improve the diagnosis rate of early gastric cancer, people with high risk of gastric cancer should be examined regularly. Those with chronic blood loss in the gastrointestinal tract of unknown origin; those with significant weight loss and loss of appetite in a short period of time should undergo stomach-related examinations to prevent missing the diagnosis of gastric cancer. Gastroscopy is a necessary examination to confirm the diagnosis of gastric cancer, which can determine the location of tumor and obtain tissue specimens for pathological examination. If necessary, pigmented endoscopy or magnification endoscopy can be used as appropriate. 2.Ultrasound gastroscopy: It can help to evaluate the infiltration depth of gastric cancer and determine the metastasis of perigastric lymph nodes, and is recommended for preoperative staging of gastric cancer. This examination is necessary for those who intend to perform minimally invasive surgery such as endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD). 3.Barium X-ray meal examination: this examination is painless and easily accepted by patients, and the new digital X-ray gastrointestinal imaging can diagnose gastric cancer more accurately. 4.Spiral CT: Multi-row spiral CT scan combined with three-dimensional reconstruction and simulated endoscopy technology is a new non-invasive examination method, which is helpful for the diagnosis and preoperative clinical staging of gastric cancer. 5.PET: It can show the whole body tumor lesions, but sometimes it is difficult to distinguish from inflammatory lesions. 6.Laparoscopy: For those who suspect peritoneal metastasis or intra-abdominal dissemination, laparoscopy can be considered.