Objective To summarize the research progress of sialic acid-binding immunoglobulin-like lectin-15 (Siglec-15) in the field of tumor immunity, in order to provide a new theoretical basis for tumor immunotherapy. Methods "Siglec-15, tumor, immunoregulation, signal pathway, immunotherapy" was used as the key words to systematically search the literature published in China National Knowledge Infrastructure(CNKI) and PubMed database from 2013-01-01 to 2023-12-31. Inclusion criteria; (1) discovery and molecular characteristics of Siglec-15: (2) the mechanism of Siglec-15 in tumor immune regulation and related signaling pathways； (3) the prospect of Siglec-15 immunotherapy. Exclusion criteria: literature with low quality and obsolete data. A total of 51 articles were included for analysis. Results Existing research indicates that Siglec-15 is highly expressed in various tumor cells as well as tumor-associated macrophages (TAMs). It induces tumor immune evasion by suppressing the activation and proliferation of T cells. Additionally, Siglec-15 can regulate the tumor microenvironment by mediating specific molecular signal pathways. Currently, multiple Siglec-15-related drugs with anti-tumor activity are actively being developed, providing new avenues for tumor immunotherapy. Conclusion In recent years, with the emergence of resistance to programmed death-1 (PD-1) and its ligand (PD-L1) antibodies, Siglec-15 is considered an emerging target that may serve as an alternative or synergistic approach to anti-PD-l/PD-Ll therapy, holding promise for significant contributions. © 2024 Chinese Journal of Cancer Prevention and Treatment, Editorial board. All rights reserved.