Abstract: Gastric cancer is a malignant tumor characterized by high morbidity and mortality. With the development of molecular biology technology and the emergence of various new omics detection techniques in recent years, molecular epidemiologists of gastric cancer have conducted extensive studies on the genetic and host factors, as well as gene-environment interactions associated with exposure to environmental factors in gastric cancer. In addition, epidemiologists have studied the evolution of precancerous gastric lesions, the development of gastric cancer, and explored relevant biomarkers to provide major evidence for the prevention and control of gastric cancer. This review summarizes the latest advances in the molecular epidemiology of gastric cancer, including existing evidence in studies for candidate-approach-based serum/plasma biomarkers, genome-wide association, whole-exome sequencing, tissue microarrays, as well as studies on metabolomics and microbiomes. We expect to provide insights into the future of molecular epidemiology studies in gastric cancer, promoting etiologic research, and the precise prevention and control of gastric cancer.