Protein arginine methyltransferase (PRMT) can methylate a variety of proteins, including histones and non-histones, affecting a variety of cellular processes such as transcription, RNA splicing, DNA repair, and cell cycle control. The activity of PRMT is affected by a variety of regulatory mechanisms, and its abnormal expression plays an important role in the development of the diseases, especially in tumors such as breast cancer and leukemia. PRMT has a unique value in the diagnosis or treatment of tumors. With the further exploration of PRMT methylation mechanism, PRMT selective inhibitors have made some progress. PRMT-specific inhibitors are expected to be targeted drugs for the treatment of tumors.