In recent years, the inhibitors for immunity checkpoint molecules, programmed death-1/programmed death ligand-1 (PD-1/PD-L1), have obtained encouraging results in solid tumor therapy. PD-1, which is mainly expressed in activated T and B cells, plays a vital role in preventing autoimmune and auto-inflammatory reactivity in the normal host. However, PD-1/PD-L1 expres-sion is very high in the tumor microenvironment, which makes T cell activity be suppressed excessively. So tumor cells can escape immune response. PD-L1 expression level may be a predictive biomarker of its antibody treatment effect. Due to responses of long duration and less toxicity, a minority of patients benefit obviously from immunotherapy. In this article, we illuminated the present resear-ches on PD-1/PD-L1 antibody in treatment of malignant melanoma, lung cancer, urothelial carcinoma, renal cell carcinoma, and so on, and also discussed the biomarkers for patient selection.