Abstract: Cytotoxic substances and ionizing radiation can easily induce DNA damage, and double strand breaks (DSBs) are the main form of DNA damage. DNA damage can activate intracellular DNA damage responses and further induce related biological effects, such as DNA damage repair and cell cycle arrest. Homologous recombination (HR) is the primary DSB repair mechanism in eukaryotes. Abnormal expression of Rad 51C, which is a key factor in the HR pathway, may result in DNA repair disorder, genomic instability, and eventually lead to tumor formation. In recent studies, researchers considered Rad 51C as a potential target for cancer treatment. We reviewed the research progress on Rad 51C in DNA damage repair and radiotherapy.