Objective To investigate and evaluate the diagnostic value of transcranial doppler ultrasound (TCD) on brain death in patients with severe craniocerebral injury.Methods Forty-two cases of severe craniocerebral injury from Affiliated Hospital of Jining Medical University were divided into brain death group and survival group,according to the clinical prognosis.TCD was conducted to examine brain blood flow numerical and changed characteristics of the spectrum.Average blood flow velocity (Vm),pulse index (PI),diastolic blood flow in reverse (reverberating flow) and small systolic peaks in early systole (wave of spikes)were documented.TCD parameters were compared between the two groups with t test.Results In the brain death group,frequency of reverberating flow was 86.67％ and frequency of wave of spikes was 13.33％.In survival group,frequency of reverberating flow was 14.81％ and no wave of spikes was recorded.The difference in frequencies of reverberating flow and wave of spikes between the two groups was significant(x2 =28.25,P ＜0.01).The average speed of bilateral middle cerebral artery blood flow in brain death group((20.02±13.96) cm/s) was significantly reduced compared with survival group((56.81± 16.84) cm/s,t=2.30,P＜0.05).Pulse index (PI) values in brain death group (4.02±3.49)were significantly increased compared with survival group (1.24±1.03) (t=2.10,P＜0.05).Conclusion Reverberating flow or wave of spikes is an important marker for brain death in patients with severe craniocerebral injury.TCD may be applied to clinically confirm the diagnosis of brain death.