Carbon fibers (CFs) were prepared from polyacrylonitrile fibers pre-irradiated with gamma-ray irradiation in air prior to heat treatment and then by continuous stabilization and carbonization. The structural changes of fibers during heat treatment and the mechanical properties of the resultant CFs were investigated using dynamic mechanical analysis, wide-angle X-ray diffraction, small-angle X-ray scattering, and universal testing machine. It is found that not only the stabilization time was shortened with the increasing absorbed doses, but also the preferred orientation of carbon layers in the CFs was increased initially with the increasing absorbed doses and then decreased. Consequently, the tensile strength and Young's modulus of CFs were increased by 13.2 and 2.6 % at an appropriate dose, respectively, in which skin-core structure in CFs was relieved according to SEM images. Hence, it is believed that irradiation technology-assisted stabilization has a significant potential in CF industry.