Objective: This study aims to investigate the therapeutic effects and mechanisms of x-ray treatment on rats following spinal cord injury (SCI). Methods: Forty-six female Sprague-Dawley rats were subjected to spinal cord injury using the modified Allen weight-drop method. The animals were randomly divided into six groups. Two of the animal groups were irradiated with 10 Gy at the lesion site; another two groups were irradiated with 20 Gy; and the last two groups without irradiation were regarded as the sham group. One of the each of two animal groups was euthanized at different time points at 4 and 12 weeks, respectively, after irradiation. Spinal cord calluses were assessed using kinology and electrophysiology and histology methods. Results: In all of the groups, the neurofilament (NF) counts at 14 weeks were found to be higher than that at 6 weeks after SCI. Both 10-Gy irradiated and 20-Gy irradiated groups were higher than those of the sham group at each time point (P < 0.05). The myelin basic protein (MBP) count decreased at 14 weeks after SCI in the irradiated groups (P < 0.05) but increased at 14 weeks in the sham group (P < 0.05). Furthermore, the MBP count of the irradiated groups was lower than that of the sham group at 14 weeks (P < 0.05). The glial fibrillary acidic protein (GFAP) and Nogo-A counts at 14 weeks were higher than those at 6 weeks in all the groups (P < 0.05), and there was no statistical significance with kinology and electrophysiology tests in all groups. Conclusions: A self-repair mechanism exists after spinal cord injury, which lasts at least 14 weeks. X-ray therapy promotes the regeneration of the spinal cord system after injury.