Abstract: Recently, many radio oncology researchers had gained some good curative effects on DNA damage repair inhibited and tumor cell death increased by blocking key control genes in the course of DNA repair with specific blocking agents. Otherwise, the blocking agents have many defects, which extremely limited its application on curing tumor. Since small interference RNA (siRNA) technology was discovered, its powerful function of blocking expressible specific protein in eukaryocytes was attented by many researchers. Meanwhile, this technology admirably resolved mentioned above problems caused by using the blocking agents, which provided a new way for tumor radio gene therapy.