The experiment used dormancy of the potato variety of L-55 different radiation dosages of ^60Co-γ ray radiation mutagenesis to the tuber and T-66, in order to breed the excellent germplasm resources or new variety. The results indicated that the variation degree of main agronomic characters of the same potato variety M2 by the different radiation dosages of ^60Co-γ ray is different, and that the variation degree of main agronomic characters of the different potato variety M2 by the same radiation dosages of ^60Co-γ ray is different. The mutagenesis of ^60Co-γ ray is a quite effective means to improve some characters, for example the precocious, the disease resistance, the high yield and the chlorophyll content. There are difficulties in the radiation mutagenesis breeding of the potato because most mutation of the potato are the recessive mutation. The optimum radiations dosages ranges of ^60Co-γ ray mutation to potato are from 10GY to 15GY. 41 superior plants are chosen from the M2 descendant for the further identification. It is an effective breeding method to mutate the potato by using the ^60Co-γ ray.