T-cell exhaustion is the loss of T-cell function in patients with chronic infections and cancer.Pro-longed exposure to inflammatory signals or persistent antigens causes T cells to gradually lose their effector function and memory characteristics.Exhausted T cells affect cancer prognosis and the outcome of viral infection,and the severity of ex-haustion has a range of adverse effects on cancer prognosis.The extensive development of tumor immunotherapy has driven current research to understand the mechanism of T-cell exhaustion as well as to optimize tumor immunotherapy regimens by reversing T-cell exhaustion.This article reviews the mechanism of T-cell exhaustion,the characteristics of exhausted T cells,and the reversal of T-cell exhaustion status.