In the tumor microenvironment, the interaction of programmed cell death protein 1 (PD-1) and programmed death-ligand 1 (PD-L1) can promote the immune escape of tumor cells. The application of PD-1/PD-L1 blockade can restore host immune function to efficiently identify and kill tumor cells. In recent years, PD-1/PD-L1 blockade has shown remarkable clinical effects in a variety of tumors and U.S. Food and Drug Administration has approved nivolumab and pembrolizumab for the treatment of unresectable/metastatic melanoma, non-small cell lung cancer and etc. Hence, a growing number of clinical trials on PD-1/PD-L1 blockade for advanced gastric cancer have been carried out, and the overall survival and objective response rate of most trials are promising. This paper reviewed PD-1/PD-L1 signaling pathway, the relationship between the of PD-L1 and the classification and prognosis of gastric cancer, and the clinical results of PD-1/PD-L1 blockade in advanced gastric cancer.