1.Autonomous respiratory arrest. 2.Irreversible deep coma. 3.Disappearance of brainstem reflexes 4.Transcranial Doppler ultrasonography (TCD) detects the typical manifestation of back and forth oscillation of blood flow, suggesting complete cessation of intracranial blood flow, which can be used as a diagnostic basis for brain death. 5.Electroencephalogram (EEG) is flat and straight. EEG must be closely observed according to the operation protocol, if the results observed within 12 hours (each interval of 6 hours or more) are flat and straight, brain death can be considered; if dynamic EEG can be done, a continuous flat and straight line up to 6 hours can be diagnosed as brain death. 6. The somatosensory evoked potential (SEP), brainstem auditory evoked potential (BAEP), and visual evoked potential (VEP) showed a flat resting electrical state.