Gastric cancer is a malignant tumor originating from the epithelium of gastric mucosa, and the symptoms are different due to different etiologies. 3.Blood test, including blood routine, biochemistry, tumor markers, etc. 4.Barium contrast, which is the first and main method of gastrointestinal tumor examination. 5.Gastroscopy, which can directly observe the lesions of gastric mucosa in early stage, such as gastric mucosal ulcer and bulging lesions, and biopsy can be performed at the same time to take a clear diagnosis. 6.CT examination, which is generally used for advanced gastric cancer patients to understand the metastasis of cancer cells. It is used to understand the metastasis of cancer cells, among which pathological biopsy can be taken through gastroscopy, and the examination result is the gold standard for the diagnosis of gastric cancer. Clinically, only a clear pathological diagnosis can confirm the diagnosis of gastric cancer, while other examinations are auxiliary examinations and cannot confirm the diagnosis of gastric cancer.