This study designed to establish a complete transaction of dorsal corticospinal tract SD rat model and discuss about the effect of low power laser irradiation on neuron regeneration after acute spinal cord jury. 30 SD rats were equally and randomly divided into two groups. Complete transaction of dorsal corticospinal tract was done to each rat. Then,irradiation group was undertaken local consecutive low power laser irradiation 15min after surgery and lasted for 14 days. Compared to irradiation group,there was no postoperative irradiation after surgery in control group. After infusion,1 cm length of spinal cord,which was above and below T8 level,were extracted on the 3rd,7th and 14th day after surgery. Hematoxylin and eosin stain and immunofluorescence stain were use for evaluation. At two weeks after surgery,the value of gial scar area was less than that of control group with statistically significant differences. There was intensive expression of glial fibrillary acidic protein (GFAP) and Chondroitin Sulfate (CS56) around the injury area in control while sparsate distribution of GFAP and CS56 was found in irradiation group. An amount of fibriform Neurofilament (NF) expression associated with regularly Growth Associated Protein 43 (GAP43) expression were located around the injury area,However,scrambled and slight GAP43 and NF expression were found in control. The result of our study showed that low power laser irradiation can improve regenerate of axon and decrease formation of gial scar area during the acute stage of spinal cord injury.