60,Co γ-rays irradiation method was applied to prepare nano-particle copper in aqueous solution. The nano-particles with different sizes were prepared by use of irradiation with different absorbed doses. The samples were analyzed with X-rays powder diffraction (XRD), electron microscopy (TEM) and laser scattering particle size distribution analysis (LSPSDA), which were used to determine the constitution, shape and size distribution of the particle, respectively. It has been found that average size of copper nano-particle decreases with the increment of radiation absorbed dose. The sample is a mixture of cuprous oxide and pure copper when absorbed dose is low. And pure copper nano-particles can be obtained at 400 kGy. The morphology of the nano-copper particle can not be affected by absorbed dose and most particles are spherical.