Diagnosis of gastric cancer is as follows: 1. Combined with medical history: chronic abdominal pain, belching and other manifestations of peptic ulcer; 2. Physical examination: the stomach is located in the left upper abdomen of the human body, which is in the center position, and there can be left upper abdominal pressure and pain when examined and pressed; 3. Imaging examination: fiberoptic endoscopy, barium meal, abdominal ultrasonography, CT, MRI; fiberoptic endoscopy can observe the location and scope of lesion and take out the tissue cells of the lesion for pathological diagnosis; X-ray barium meal is a painful examination, which is easy for patients to accept, especially for the elderly or patients who are afraid of gastroscopy; abdominal ultrasonography can observe the structure of surrounding tissues and organs to find out whether there is any cancer. X-ray barium meal examination is painless and easy to be accepted by patients, especially for elderly patients or patients who are afraid of gastroscopy; abdominal ultrasound can observe the structure of surrounding tissues and organs to find out whether there are infiltration and metastasis of cancer cells; CT and MRI examinations are decisive for the diagnosis and staging of gastric cancer, which can be used for clinicopathological staging and clinical diagnosis of gastric cancer through the structural changes in the gastric wall mucous membrane and the enlargement of the liver, pancreas, spleen and other lymphatic organs. CT and MRI examinations are decisive for the diagnosis and staging of gastric cancer.