Toll样受体9(TLR9)是细胞内主要DNA感受器之一,主要识别病原体源性和损伤细胞来源的Cp GDNA。DC细胞中TLR9的激活可进一步导致CD8~+T细胞的激活从而发挥肿瘤抑制作用。然而,TLR9在肿瘤中的作用却很复杂,可能与肿瘤类型和TLR9表达的细胞类型相关。然而直到现在,关于这方面研究仍然缺乏系统的综述。在此,我们从临床意义到基础机制及临床治疗方面总结归纳TLR9在肿瘤发生发展中的复杂作用。 Toll-like receptor 9 (TLR9) is one of the major DNA receptors in cells and mainly recognizes Cp GDNA derived from pathogen-derived and damaged cells. The activation of TLR9 in DC cells can further lead to the activation of CD8 ~ + T cells to exert tumor inhibition. However, the role of TLR9 in tumors is complex and may be related to tumor types and cell types expressed by TLR9. However, until now, there is still a lack of systematic review on this aspect. Here, we summarize the complex role of TLR9 in the development of tumors from the clinical significance to basic mechanisms and clinical treatment.