Abstract: With the research progress on the biology and pathogenesis of cancer, immune checkpoint inhibitors (ICIs) have come into being, bringing a new hope for the survival of patients with advanced cancer and opening a new era of cancer immunotherapy. However, with the wide application of immunotherapy in clinical practice, ICI-related adverse events (irAEs) have gradually emerged and are widely known by first-line clinicians. ICIs primarily activate T cells that can attack normal tissues and organs in the body and cause a variety of adverse reactions. Checkpoint inhibitor pneumonitis (CIP) is one of the rare complications with poor prognosis in irAEs. This article reviews the therapeutic mechanism of some ICIs; the incidence, risk factors, pathogenesis, and clinical and imaging manifestations of CIP; and the classification and treatment management of CIP.