Abstract: Aberrant modification of histone and DNA methylation are important fields in epigenetic research. Interaction between them often results in the activation or inhibition of specific genes. Methylation level of histone H3 lysine 27 and its methyltransferase EZH2 are closely correlated with specific classification of B-cell non-Hodgkin's lymphoma (B-cell NHL) and its prognosis. This paper emphatically introduces the roles that H3K27me3 and EZH2 might play in the onset and development of B-cell NHL, and the possible mechanism as well.