Abstract: With the gradually in-depth research of immune checkpoint, the checkpoint inhibitors, such as programmed death-1(PD-1) inhibitors, programmed death–ligand 1(PD-L1) inhibitors and cytotoxic T lymphocyte-associated protein-4(CTLA-4) inhibitors, had made breakthroughs in clinical research. Although the FDA had approved several immune checkpoint inhibitors listed, there are still many problems and deficiencies in the use of checkpoint inhibitors for non-small cell lung cancer (NSCLC). This paper reviewed how immune checkpoint signaling pathway mediated tumor immune escape, the significance and limitations of PD-L1 as a biomarker for the prediction of therapeutic effect of PD-1 / PD-L1 monoclonal antibody on NSCLC, other potential biomarkers and the mechanisms of immune resistance.