Abstract: DNA methylation is a special epigenetic event that constitutes an important mechanism regulating gene expression, and plays an important role in the occurrence and development of diseases. In recent years, with the advances in basic medical research, researchers have discovered hypermethylation of genes in hematological tumors, especially malignant lymphoma, and steady progress has been made in the discovery and clinical development of DNA methylation modulating drugs. DNA methyltransferase inhibitors (DNMTIs) are epigenetic drugs that exert anti-tumor effects by interfering with the process of DNA transcription. These drugs have become a new method of antitumor therapy. To date, available DNMTIs include decitabine and azacytidine that have shown promising efficacy in the treatment of hematologic malignancies and solid tumors. This review focuses on the mechanisms by which DNA methylation inhibitors affect malignant lymphoma, and describes the progress in clinical research.