Platinum-based chemotherapy has long been the standard first -line treatment for small cell lung cancer. In recent years immunotherapy has rapidly advanced in the field of lung cancer offering new hope for small cell lung cancer patients. However the response rate and duration of response to immunotherapy remain suboptimal primarily due to the limitations of current biomarkers for predicting immunotherapy efficacy in small cell lung cancer such as low sensitivity and weak specificity. therefore there is an urgent clinical need to identify more efficient biomarkers. The research on immune checkpoint-related markers such as PD-L1 and B7-H3 has shown that the expression levels of immune checkpoint proteins are closely related to the response to immunotherapy in some patients. In terms of tumor-specific biomarkers tumor mutation burden TMB has been widely utilized as a key indicator for predicting the efficacy of immunotherapy while molecular subtyping of small cell lung cancer offers new perspectives for optimizing treatment strategies. Furthermore tumor microenvironment - related biomarkers including the inflammatory T cell gene expression profile T cell inf GEP and tumor - infiltrating lymphocytes TILs provide additional possibilities for evaluating immune responses. In the field of non-invasive testing peripheral blood biomarkers such as the neutrophil-to-lymphocyte ratio NLR and lung immune prognostic index LIPI have demonstrated promising predictive value for therapeutic outcomes. This article reviews the research progress of potential biomarkers in the field of small cell lung cancer in recent years aiming to explore suitable biomarkers for identifying patients who will derive long-term benefit realizing individualized precision treatment improving patients' quality of life and prolonging survival time.