Abstract: Gastric cancer is one of the major types of cancer threatening human health worldwide. Its pathogenesis has not been fully elucidated, and patients are often diagnosed at an advanced stage. The oral cavity is the second largest microbial pool after the intestine in the human body, and thus the relationship between oral bacteria and human health is attracting increasing interest. Oral bacteria are closely related to gastric cancer and potentially serve as noninvasive diagnostic screening biomarkers for the disease. Imbalance in and displacement of these bacteria can promote the occurrence and development of gastric cancer. Hence, this article reviews the association between oral bacteria and gastric cancer, aiming to provide a basis for further elucidating the pathogenesis of gastric cancer and screening it early through noninvasive methods and serve as a reference for subsequent related research.