Abstract: Ataxia-telangiectasia(AT) is caused by the mutation of AT(ATM)mutated gene and it is characterized by high radiosensitivity of AT calls. Progress in the research of AT is reviewed in this paper, including the clinical symptoms of this disorder, as well as the localization, structure and function of ATM gene, and summarized the studies on the gene mutation and high radiosensitivity of AT cells in recent years. Further study to ATM gene may provide an important entrance for radiosensitivity-related therapy.