RNA methylation plays a significant regulatory role in various of physiological activities. 2'-O-methylcytidine (Cm) is one of the representative 2'-O-methylation and base-methylation modified epigenetic marks of RNA. 2'-O-Methylcytidine is derivative of the nucleoside residue cytidine with a methyl group attached to the 2'-oxygen position. 2’-O-methylcytidine was found to be related to various diseases including cancer, and it might have great potential to be novel biomarkers for detection of breast cancer in the early stage. In addition, 2'-O-methylcytidine showed as an inhibitor of RNA polymerase from the hepatitis C virus (HCV). And 2’-O-methylcytidine was involved in plant stress responses.