Objective: To investigate the expression profile of CCR8 in tumor-infiltrating Tregs within ovarian cancer and to elucidate its impact on Treg differentiation. Methods: C57BL/6 mouse model bearing ID8 ovarian cancer cells was established. Flow cytometry assays were conducted to measure the expression ratios of CCR8 on Tregs in mouse tumor tissues, spleen, and peripheral blood, as well as the expression of immune checkpoints PD-1, CTLA-4, ICOS, and LAG-3 on CCR8+Tregs. Results: The tumors in the ovarian cancer-bearing mice exhibited a marked increase in CCR8 expression on Tregs when compared to spleen and peripheral blood. Additionally, CCR8+ Tregs demonstrated elevated levels of immune checkpoint markers relative to CCR8-Tregs.The conformational inhibitor AZ084 was effective in suppressing the differentiation of Naive CD4+ T cells into Tregs in the mouse spleen. Conclusion: CCR8+ Tregs are predominant among tumor-infiltrating Tregs. CCR8 acts as a primary biomarker for Tregs infiltrating ovarian cancer, and conformational alteration of CCR8 protein can inhibit Treg differentiation. This suggests that targeting the depletion of CCR8+ Tregs may provide a new avenue for mitigating the immunosuppressive status within the ovarian cancer microenvironment.