This review summarizes the characteristics, subpopulations, and immunosuppressive mechanisms of tumor-infiltrating regulatory T cells (Ti-Tregs) and discusses current strategies targeting these cells for improved antitumor responses. Regulatory T cells (Tregs) are crucial components of the tumor immune environment and have significant therapeutic potential. However, nonspecific inhibition of Tregs can lead to autoimmune reactions and severe side effects. Therefore, precise targeting and inhibition of tumor-infiltrating Tregs are essential. Tregs exhibit diverse subpopulations, including natural Tregs (nTregs), peripheral Tregs (pTregs), and induced Tregs (iTregs), with distinct functional and phenotypic characteristics. Tregs suppress antitumor immune responses through various mechanisms, including the expression of immune checkpoint molecules like CTLA-4, PD-1, and others, as well as the secretion of immunosuppressive cytokines such as IL-10, TGF-β, and IL-35. Additionally, Tregs modulate the tumor microenvironment through chemokine receptors, metabolism, and angiogenesis. Targeting Tregs can enhance antitumor immunity by reducing their immunosuppressive effects. Current strategies include the use of monoclonal antibodies targeting Treg-specific molecules, such as CD25, CTLA-4, and PD-1, as well as the development of drugs that inhibit Treg function or recruitment. These approaches aim to improve the efficacy of immunotherapy by enhancing the activity of effector T cells and reducing the suppressive effects of Tregs. The review also highlights the importance of understanding the tumor immune microenvironment and selecting appropriate therapeutic strategies for different tumor types. Overall, targeting Tregs represents a promising approach for advancing immune-based cancer therapies.This review summarizes the characteristics, subpopulations, and immunosuppressive mechanisms of tumor-infiltrating regulatory T cells (Ti-Tregs) and discusses current strategies targeting these cells for improved antitumor responses. Regulatory T cells (Tregs) are crucial components of the tumor immune environment and have significant therapeutic potential. However, nonspecific inhibition of Tregs can lead to autoimmune reactions and severe side effects. Therefore, precise targeting and inhibition of tumor-infiltrating Tregs are essential. Tregs exhibit diverse subpopulations, including natural Tregs (nTregs), peripheral Tregs (pTregs), and induced Tregs (iTregs), with distinct functional and phenotypic characteristics. Tregs suppress antitumor immune responses through various mechanisms, including the expression of immune checkpoint molecules like CTLA-4, PD-1, and others, as well as the secretion of immunosuppressive cytokines such as IL-10, TGF-β, and IL-35. Additionally, Tregs modulate the tumor microenvironment through chemokine receptors, metabolism, and angiogenesis. Targeting Tregs can enhance antitumor immunity by reducing their immunosuppressive effects. Current strategies include the use of monoclonal antibodies targeting Treg-specific molecules, such as CD25, CTLA-4, and PD-1, as well as the development of drugs that inhibit Treg function or recruitment. These approaches aim to improve the efficacy of immunotherapy by enhancing the activity of effector T cells and reducing the suppressive effects of Tregs. The review also highlights the importance of understanding the tumor immune microenvironment and selecting appropriate therapeutic strategies for different tumor types. Overall, targeting Tregs represents a promising approach for advancing immune-based cancer therapies.