Exhausted CD8 + T cells (CD8 + Tex) are a distinct subpopulation formed from naive CD8 + T cells under conditions of sustained high antigen stimulation. Initially, naive CD8 + T cells can differentiate into functional cytotoxic cells and exert anti-infective and anti-tumor effects upon short-term antigen stimulation. However, sustained high antigen stimulation will make effector CD8 + T cells progressively differentiate into terminally CD8 + Tex cells and irreversibly lose effector function. Unlike memory and effector T cells, CD8 + Tex cells have a unique transcriptional program. Numerous studies are attempting to map a detailed differentiation landscape of CD8 + Tex cell subsets, aiming to maximize the number of effector T cells in the future by targeting individual subsets or individual differentiation stages in CD8 + Tex cells without damaging the effector cells. This article reviewed the progress in CD8 + Tex cells from the aspects of transcriptional dysregulation, metabolic reprogramming, subpopulation typing and clinical application, aiming to provide more CD8 + T cell-based therapeutic strategies for tumor.