Objective：To observe the early apoptosis and its dynamic changes after traumatic brain injury(TBI) in Sprague-Dawley rats. Methods: The moderate brain injury model was established by a fluid-percussion brain injury device; animals in control group were only cannulated but not injured. Then the injured animals were sacrificed 6, 24 and 48 hours after injury. Flow cytometer and electron microscope were used to observe the apoptosis of nerve cells. Results: Flow cytometer showed that the early apoptosis of nerve cells occurred in left parietal cortex 6 hours after TBI, with an apoptotic ratio being 21.97%, significantly higher than that in the control group at the same time point（P<0.01）. The apoptosis reached its peak 24 hours after TBI, with an apoptotic ratio being 65.90%, significantly higher than that in the control group at the same time point（P<0.01）; there was no significant difference between those of 24 hours and 48 hours after TBI（P>0.05）. Electron microscope showed apoptosis of nerve cells in the left parietal cortex 24 hours after TBI. Conclusion: Early apoptosis of nerve cells may occur 6 hours after TBI, which is earlier than previously reported.