Abstract: Mixed lineage leukemia 1(MLL1) is a member of the "SET" histone methyltransferases family.MLL1 methyltransferase complex, consisting of MLL1, WDR5, RbBP5, Ash2L and DPY-30, regulates methylation level of histone H3 lysine 4 and is essential for the development of human hematopoietic system and self-renewal of blood cells.As an oncogenic protein produced by the translocation of MLL1 gene, the MLL1 fusion protein has been found in some patients with leukemia.Complete MLL1 enzyme complex is required to perform histone demethylation effect, therefore, targeting the protein-protein interaction of MLL1-WDR5 has become a potential strategy for the treatment of leukemia induced by MLL1 fusion protein.This review systematically summarizes the biological mechanism, structural information and inhibitors of MLL1-WDR5 protein-protein interaction, with a perspective based on previously reported data, aiming to provide some reference for further investigation.