AbstractBackgroundAs one of the most aggressive neuroendocrine tumors, small cell lung cancer (SCLC) has the most disappointing prognosis of all lung cancers. Although SCLC responds well to initial chemotherapy, the majority of patients experience disease recurrence within one year, and patient survival is poor. It is still necessary to explore the application of ICIs in SCLC since the beginning of the road to immunotherapy, which broke the 30‐year treatment deadlock of SCLC.MethodsWe searched PubMed, Web of Science, and Embase with search terms such as "SCLC", "ES‐SCLC", "ICIs", and "ICBs", and categorized and summarized the relevant literature obtained, and we compiled the latest progress about the application of ICIs in SCLC.ResultsWe listed 14 clinical trials on ICIs, including 8 clinical trials on first‐line SCLC treatment, 2 clinical trials on second‐line SCLC treatment, 3 clinical trials on third‐line SCLC treatment, and 1 clinical trial on SCLC maintenance treatment.ConclusionICIs in combination with chemotherapy can improve OS in SCLC patients, but the extent to which SCLC patients can benefit from ICIs is limited, and ICIs' combination treatment strategies still need to be continuously explored.