Abstract: Tumor immunotherapy, mainly programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) inhibitor and cytotoxic T lymphocyte antigen 4 (CTLA-4) inhibitor that were widely used these years, may effectively prolong the overall survival of patients with various tumors. However, immune checkmate inhibitor may also lead to immune-related adverse events (irAEs). Immune checkpoint inhibitor related pneumonitis is a sort of irAEs, which may cause therapy cease, therapy failure, and even life-threaten in a few cases. Understanding the clinical characteristics of immune checkpoint inhibitor related pneumonitis, early recognition and diagnosis, and appropriate treatment are of great significance to avoid affecting the prognosis and prolong the life of tumor patients.