Abstract: Ribonucleotide reductase (RR) regulates dNTP production, catalyzing the reduction of ribonucleotide into deoxyribonucleotide diphosphate, which is essential in DNA synthesis and cell proliferation. RR overexpression is related with the tumorigenesis and tumor progression. At present, RR inhibitors have been used on clinical cancer treatment, and new anticancer drugs have been developed targeting RR and its subunits, which may provide new options for cancer therapy. This review discusses the structure and function of RR, the role of RR on cancer therapy, and future application of RR inhibitors.