Abstract: MicroRNAs (or miRNA) are a noncoding regulated endogenous RNA molecules with the length of 22nt. As negative regulators, they were used to regulate the gene expression through sequence-specific translational suppression or mRNA cleavage, and participate in a series of key biological processes, such as cell development and proliferation, apoptosis, and haematopoiesis etc. Recently, researchers have found that many microRNAs have oncogenes or tumor sup-pressor genes, and can play an important role in the occurrence and development of tumor. Diffuse large B cell lymphoma (DLBCL) is a most common malignant lymphoma, which accounts for 30% of the NHL. DLBCL is defined as the malignant lymphoma which originates from the B cells, has big tumor cells, shows aggressive clinical manifestations, and needs che -motherapy of high efficiency. This kind of tumor occur inside or outside lymph node, and can be primary or secondary in the evolution of other low-grade malignant lymphomas. Therefore, there exists an extremely heterogeneity in the clinical mani-festation, morphology, immunophenotype and genetic characteristics of the carcinoma. Now, researchers have found that several kinds of microRNA directly involved in the occurrence and development of diffuse large B cell lymphoma, and there is a correlation between the microRNA expression and molecular subtypes of diffuse large B-cell lymphoma. As a kind of new molecular target, miRNA has a broad prospect in the application for diagnosis and biotherapy of the diffuse large B cell lymphoma.