Objective: The purpose of this study is to explore the immunosuppression of nuclear factorkappa B (NF-κB) by intragastric brazilein in spinal cord segments connected with injured sciatic nerve in mice. Methods: Healthy adult BALB/c mice underwent unilateral sciatic nerve interruption and anastomosis and then were treated with physiological saline (blank group), high dose, middle dose and low dose of brazilein in separate groups. The potential amplitude and motor nerve conduction velocity (MNCV) were measured. Myelin was assayed by immunohistochemical staining. NF-κB levels were detected by Western blotting and real-time PCR. Results: The potential amplitude and MNCV in the high and middle dose groups were significantly higher than in the low dose group and blank group. Myelin of the high dose and middle dose groups had more integrity. NF-κB was activated in spinal cord L4–6 connected with injured sciatic nerve. During the survival time of 12 h, 24 h, 3 d, 5 d and 1 w, NF-κB expression of the high dose group and the middle dose group were significantly lower versus the low dose and bland groups (P < 0.05). Conclusion: Brazilein can inhibit the immune activation of NF- κB in neurons in spinal cord L4–6 connected with injured sciatic nerve, which promotes nerve regeneration.