Immune checkpoint inhibitors are fully humanized monoclonal antibodies, which mainly target programmed death-1 (PD-1), programmed death ligand-1 (PD-L1) and cytotoxic T-lymphocyte antigen-4 (CTLA-4). The inhibitors are approved for the treatment of patients with non-small cell lung cancer with effective and durable responses. This review summarized the mechanism and the clinical progress of these drugs in treatment of lung cancer, and the prognostic and predictive roles of related biomarkers.