Abstract: Histone deacetylase inhibitors (HDACI) can improve the acetylation status of histone N-terminal, which will exert the effect on treatment. The N-terminal of histone modifications belongs to the category of epigenetics. Epigenetics mainly refers to the study of the heritable variation without change in DNA sequence. HDACI had been paid much attention as a new non-cytotoxic anti-cancer targeted drug. Thus, the application of this drug in clinical research is widespread. After the U.S. Food and Drug Administration approved two HDACIs for the treatment of cutaneous T-cell lymphoma, the clinical applications of HDACI in other subtypes of T-cell lymphoma have obtained increasing attention. Studies on the mechanism of HDACI provide the theoretical basis for the application of HDACIs in other subtypes of T-cell lymphoma. In this article, we reviewed the mechanism and clinical trials of HDACIs on the treatment of T-cell lymphoma.