【Abstract】　Objective To observe the expression of granzyme B (Gra-B), perforin and CD8+ T cell in rat brain to investigate how they takes part in the neuronal death mechanism of cardiac arrest resuscitation. Methods Male Wistar rats were randomly divided into sham-operation group and resuscitation group. Cardiac arrest was induced by clamping the tracheal tube for 6 min. The Beam-Walking Test and the Hanging Wire was used to detected CA-CPR induced neurologic and motor deficits. BBB permeability was detected by Evans blue (EB) content in brain tissue. The expressions of CD8+ T cell, Gra-B and perforin were determined with immunohistochemistry, Western blot and immunofluorescent technique. Results Compared to the sham-operated group, sensorimotor function and muscle strength of CPR rat was significantly decreased, the difference reached to the top level at 3d（4.00±0.70 vs. 0.89±0.34，P<0.01）, and then began to recover at 4d and 5d. We observed that the BBB permeability was significantly increased, CD8+ T cell infiltrate the cortex and corpora striatum, as well as a significant increase in Gra-B and perforin lever within 12h of resuscitation (p<0.01). These changes reached to the peak value at 1d[（compared to the sham-operated group，Gra-B：cortex：0.95±0.08 vs.0.35±0.09；corpora striatum：1.08±0.15 vs. 0.39±0.09，allP<0.01)；perforin:( cortex：1.23+0.06 vs. 0.61±0.14,P<0.05；corpora striatum：1.23±0.06 vs. 0.47±0.14，P<0.01) ]. Gra-B was located in CD8+ cells in rat brain after CPR. Conclusions The increased BBB permeability, CD8 + T cell infiltration and the release of Gra-B and perforin may involved in mediating neuronal death after CA-CPR.