Abstract: At present, immune checkpoint inhibitors targeting the PD-1/PD-L1 axis have become a hot treatment for various cancers. Although PD-1/PD-L1 inhibitor therapy in some patients significantly improves long-term survival, there are large individual differences between patients, and some patients show primary resistance, and the overall response rate is only about 20%–30%. Pharmacogenomics studies have shown that single nucleotide polymorphisms are one of the most critical factors affecting drug efficacy and adverse drug reactions. This article reviewed the effects of gene polymorphisms on the anti-tumor efficacy and immune-related adverse reactions of PD-1/PD-L1 inhibitors, which provides reference for future research.