Objective : To study the changes of number of CD4 CD25 T cells and its significance in rats with experimental autoimmune encephalomyelitis (EAE).  Methods : EAE was induced by guinea pig spinal cord homogenate (GPSCH) , the number of CD4 CD25 T cells was detected by flow cytometry ; Through studying the pathological changes and behavior changes of rats the EAE model was determined .  Results : The successful rate of EAE in experimental group was 40%, the number of CD4 CD25 T cells of EAE rat(s5.29±4.00) was significantly lower than that in the control group(12.61±2.24), p<0.01.  Conclusions : The number of CD4 CD25 T cells in EAE rats was significantly reduced in the EAE rats . CD4 CD25 T cells may be a protective factor for the demyelinating disease of the central nervous system .