1.Endoscopy: after insertion of endoscope, pay attention to whether there is still bile and other reflux material at the pylorus of the stomach, and whether there is yellow staining of the mucosa as well as signs of congestion and edema, etc. 2.Biopsy of gastric mucosa: observe whether there is gastric microcircumference hyperplasia, mesenchymal edema, capillary dilatation of the surface of the mucosa, and inflammatory cell infiltration in the histological section, etc. 3.Radionuclide examination: after injecting radionuclide into the stomach intravenously, the radionuclide will be excreted through the liver by the bile, and it can be accurately measured by tracking the Radionuclide examination: After injecting radionuclide intravenously, the radionuclide is excreted by the liver and bile is excreted. By tracking the radionuclide, we can observe whether there is bile reflux into the stomach, and it will be positive when the ratio of radioactivity in the stomach to the total amount injected into the stomach intravenously is more than 1%. However, it is easily affected by foods with similar absorbance to bilirubin such as carrots, and it is expensive.5. 24-hour intragastric pH monitoring: it helps diagnosis in clinic, and it can respond to the acidity and alkalinity of gastric juice.6. Carbon 13 or 14 urea respiratory test: it aims to diagnose the presence of Helicobacter pylori infection.