Abstract: Histone H3 lysine 79 (H3K79) methyltransferase DOT1L plays an important role in the activation and maintenance of gene transcription; it is also essential for maintenance of embryonic development, as well as the normal function of hematopoietic system, heart and kidney. However, the over expression of DOT1L is associated with the occurring and progress of numerous malignant tumors, so more and more attention has been paid to DOT1L. Therefore, it is of great significance to study and develop inhibitors of DOT1L. The inhibitors could serve as a tool in the investigation of the biological function, and have the potential to be developed into novel anti-cancer agents in the anticancer therapy. This paper mainly describes the structure and function of DOT1L, the relationship between DOT1L and tumors as well as the latest research progress of DOT1L inhibitors; with expect to provide some useful references for the subsequent research.