5-azacytidine, also known as 4-amino-1,3,5-triazine-2-one, is the basic raw material for the synthesis of 5-azacytidine drugs. As a synthetic pyrimidine base, 5-azacytidine can combine with ribose to form 5-azacytidine, which is a kind of drug of cytosine nucleoside. It can penetrate into tumor nucleic acid as a pseudo metabolite, interfere with the physiological function of tumor cells and produce anti-tumor effect.