Diffuse large B cell lymphoma (DLBCL) is the most common subtype of invasive non-Hodgkin's lymphoma (NHL), account for 30%-40% of NHL in adults, the 5-year survival rate is approximately 25%. Although there was a standard treatment to DLBCL today, approximately 50% of patients can not be cured. As a result, it is still a diligent direction of the researchers to understand the pathogenesis of DLBCL and to explore new effective treatment. Recently, the study of microRNA is a hot topic in biology, microRNAs are a class of small non-coding RNA that have emerged to regulate various of biological processes. MiR-155 is one of the most well-known oncogenic micro-RNA, miR-155 overexpression has been documented in a number of lymphoid neoplasms, extraordinarily in DLBCL. MiR-155 can promote the occurrence of lymphoma through various signaling pathways, such as the BMP/TGF-β and RhoA pathway, it is expected to become a new target for treatment of DLBCL. This article reviews the role and possible mechanisms of miR-155 in the pathogenesis of DLBCL.