Abstract: Tertiary lymphoid structures (TLSs), as a crucial component of the tumor micro-environment, have attracted significant attention in the field of tumor research in recent years. TLSs are composed of multiple immune cells and formed under the stimulation of chronic inflammation, with their maturation process divided into different stages. They exert anti-tumor effects by mimic-king the functions of secondary lymphoid organs and generating adaptive immune responses. In terms of the prognosis of gastric cancer, the cell composition, spatial distribution of TLSs, and their combination with other indicators are all helpful in predicting the prognosis of patients. Meanwhile, the TLSs scoring system is expected to become an index for evaluating the efficacy of immuno-therapy. Treatment strategies for inducing TLSs formation have achieved certain results in animal models, but potential treatment risks require attention. The authors elaborate on formation and maturation process of TLSs, anti-tumor mechanism, value in prognostic assessment of gastric cancer and multiple tumors, prediction of immunotherapy, as well as treatment strategies for inducing the formation of TLSs.