Abstract: Gastric cancer is one of the commonest malignant tumors in the world. The application of ¹⁸F-fluorodeoxyglucose (FDG) PET/CT in gastric cancer has both advantages and limitations. ¹⁸F-FDG uptake in primary gastric cancer is closely related to cancer staging, histological classification and tumor size. Positive ¹⁸F-FDG uptake in early gastric cancer often indicates the incurability of endoscopic submucosal dissection. Maximum standardized uptake value (SUV_max) of advanced gastric cancer is significantly different between intestinal type and signet ring cell carcinoma (SRC) or diffuse type gastric cancer; SUV_max of SRC is negatively correlated with the overall survival time and disease-free survival time of patients. The sensitivity of ¹⁸F-FDG PET/CT for regional lymph node metastasis is low, but the specificity is high. Regional lymph nodes with positive ¹⁸F-FDG uptake indicate poor prognosis. ¹⁸F-FDG PET/CT can detect occult distant metastases (7.2%~10.0%), most of which (4.7%~8.8%) cannot be detected by laparoscopy. Routine application of ¹⁸F-FDG PET/CT combined with laparoscopy is of great significance in determining the staging of gastric cancer.