Abstract: The mitochondria plays a very important role in sustaining the normal physiological function, because it is the center of energy making and mitochondrial DNA (mtDNA)is the only genetic material outside the nuclear. The result of studies showed that many diseases have a close relationship with mtDNA mutation and deletion. This article reviewed the current status of research on mtDNA with tumor, radiation biological effects and aging, in order to initiate the application study of mtDNA in the cir-cle of radiation medicine.