Gastroscopic staining is a routine test in which a dye is sprayed onto the mucosa of the digestive tract and then examined endoscopically for lesions of the gastric and esophageal mucosa. Gastroscopic staining is a solution prepared with reagents or pigments to stain the mucosa of the gastrointestinal tract under gastroscopy, which is used to increase the contrast between the normal mucosa and the diseased mucosa, making the display of small lesions clearer to show lesions in the stomach and esophagus that are not easy to be detected by ordinary endoscopy, and to clarify the boundaries of the lesions as well as to assist in locating the biopsies to be taken for definitive diagnosis under gastroscopy. Common staining methods include indigo carmine stain, methylene blue stain, glacial acetic acid (edible white vinegar), Lugol’s iodine, and phenol red. Two commonly used staining routes are direct endoscopic staining and oral staining. The choice of a specific gastroscopic staining method should be made in consultation with a specialized endoscopist.