OBJECTIVE To explore the injury mechanism for white matter of spinal cord and the improvement of function after defluoridation. METHODS A total of 120 Wistar rats were separated randomly into 4 groups (n = 30 each). High flouriod group received high concentration NaF water (200 mg/L) to establish fluorosis model; control group distilled water; defluoridation group high concentration NaF water (200 mg/L) for 12 weeks and then distilled water for 12 weeks; defluoridation control group. The urinary contents of fluoride were detected at Weeks 4, 8 and 12. The first two groups were sacrificed at Week 12 while the other two groups at Week 24. The spinal cord functions were detected by BBB scale and incline plate test. Their cervical spinal cord tissues were collected and observed under electron microscope. The expression of myelin basic protein (MBP) in thoracic cord was detected by immunohistochemistry and Western blot. The comparison of measurement data was performed with F test and correlation analysis. Cytological changes of white matter in spinal cord were detected after chronic fluorosis. RESULTS The spinal functions of high flouriod and defluoridation groups were inferior to those of the control groups. But no difference existed among the groups. Pathological manifestations of chronic white matter injury of spinal cord could be found in high flouriod and defluoridation groups. The MBP expression in spinal cord of fluorosis and defluoridation groups decreased in comparison with those in control groups. But no difference existed among them. CONCLUSIONS White matter injury of spinal cord is present in chronic fluorosis rats. Defluoridation for a short time offers no recovery.