When the pepsinogen ratio <3.0ng/ml, it proves that the gastric function is reduced, suggesting the possibility of gastric cancer. Pepsinogen is the precursor of gastric digestive enzyme pepsin, which is mainly secreted by the main cells and mucus neck cells in the stomach. Pepsinogen is divided into two subtypes: pepsinogen 1 (PG1) and pepsinogen 2 (PG2), and the ratio of the two is the pepsinogen ratio. The normal value of PG1/PG2 is ≥7.5ng/ml, if it is between 3.0~7.5ng/ml, it proves that the gastric function is declining, and there may be Helicobacter pylori infection or gastritis, if it is less than 3.0ng/ml, it suggests that the gastric glands are atrophied more seriously, and it suggests that there is the possibility of gastric cancer, but to confirm the diagnosis, we also need to have other related examinations such as gastroscopy, gastric mucosal biopsy and so on. However, other related examinations such as gastroscopy and gastric mucosal biopsy are needed to confirm the diagnosis. Decrease in pepsinogen ratio only suggests the possibility of gastric cancer, and if combined with severe gastric discomfort, it is necessary to consult a doctor in time, do a comprehensive examination and take active treatment.