As one of the hallmarks of cancer cell, genomic instability induced by continuously endogenous and exogenous stress, lead to the application of radiotherapy and chemotherapy in cancer treatment. Several DNA damage repair pathways have been developed to cope with the frequent challenge of DNA insults, including Homologous recombination (HR), which comprises a series of protein complexes and nascent RNAs to repair DNA double-stranded breaks (DSBs), and the prevalent RNA methylation modifications in eukaryotic cells inevitably involve in the regulation of DNA damage repair. Thereby, aberrant RNA methylation modifications in cancer cells lead to the increasing accumulations of DNA damage, and on the other hand mediate the resistance of chemotherapy and radiotherapy. In the current review, we summarize the types of RNA methylation modifications and their roles in the process of DNA damage repair, and further discuss their application prospects in the clinical diagnosis, prognosis and therapeutic targets of tumors.