Objective To analyze the clinical features of immune checkpoint inhibitor-related pneumonia (CIP) in patients with lung cancer. Methods The case data of patients with CIP admitted to Zhongshan Hospital of Fudan University from January 2017 to December 2020 were retrospectively collected, and the basic data, clinical manifestations, imaging data, laboratory examination results, treatment and prognosis of the patients were analyzed. Results The ratio of male to female was 18:1, and the median age was 65 years (from 41 to 74 years). Fourteen patients received a programmed death protein-1 (PD-1) inhibitor and five patients received a programmed death protein-ligand-1 (PD-L1) inhibitor. The median time to CIP was 3.5 months. The respiratory symptoms of 15 patients were dyspnea in 11 cases, cough in 9 cases, chest tightness in 8 cases, fever in 4 cases, expectoration in 4 cases and hemoptysis in 2 cases. Chest CT findings mainly showed interstitial pneumonia, including 8 cases of implicit organizational pneumonia (COP), 7 cases of non-specific interstitial pneumonia (NSIP), 2 cases of acute interstitial pneumonia, and 2 cases of allergic pneumonia. C-reactive protein, erythrocyte sedimentation rate and lactate dehydrogenase were higher in CIP than before, and the difference was statistically significant. Follow-up observation was performed in 3 patients alone, 14 patients were treated with glucocorticoid alone, 2 patients were treated with immunosuppressant therapy, 19 patients had stable or more absorption of pneumonia lesions, and 5 patients had restarted immunotherapy. There were no deaths from CIP. Conclusions CIP mainly occurs in men, with slow onset, lack of specificity in clinical manifestations, and increased inflammatory indicators. Imaging findings are mainly NSIP and COP changes. Early identification, diagnosis and rational application of glucocorticoid therapy have good effects.