Abstract: In this thesis, different doses of 60Coγ rays are used to irradiate with maize seed, in the period of three-leaf, making use of CTAB to extract genome DNA of its sprout, from kinds of seedling irradiated by different doses, making restriction enzyme action on genome DNA, which helps to study damage efficiency imposed on DNA molecular by irradiation. It is shown that: with the different dose irradiation, different genome DNA among various dose would be got. The difference is more obvious especially when the dose is more than 200Gy. Irradiation not only leads to breakage of DNA molecular chain but also can change position and order of bases on DNA nucleolus chain, which also changes position of restriction enzyme. Moreover, genome DNA extracting from kinds of sprouts irradiated by the same doses has been made twice, which give the same result.