IL-10 is a pleiotropic cytokine that plays a significant role in antiviral and antitumor immunity. Potent CD8 T cells express IL-10 after stimulation by strong TCR signaling, which promotes the killing effect of CD8 T cells. However, the regulation of IL-10 expression in CD8 T cells and its signaling pathway to enhance CD8 T cell function are largely unknown. In this study, we investigated the JAK-STAT signaling molecules that regulate IL-10 expression in CD8 T cells and the JAK-STAT signaling pathway that IL-10 enhances the function of CD8 T cells through its receptor, using small molecule inhibitors and CRISPR-Cas9 gene editing. Our findings provide new insights and a theoretical basis for the immunotherapy of tumors.