Gastric cancer is one of the most serious malignant tumors in the world with high mortality and a poor prognosis. Early diagnosis is crucial to improve the survival rate of patients. Metabolomics employs high-throughput chemical analysis technology combined with chemometrics method to analyze metabolic changes of organisms, tissues, and cells. It is widely used in the screening of tumor biomarkers, disease diagnosis, and drug therapy. By consulting the literature, we summarize the research progress of metabolomics in the early diagnosis and prognosis of gastric cancer and provide a reference for the research of gastric cancer.