1, automatic respiratory arrest and no return of respiratory performance after 3 – 5 minutes after leaving the artificial respirator. The effects of CNS depressants and hypothermia need to be excluded. 2, deep coma performance, the patient does not have any voluntary activity. 3, Bilateral pupil dilatation fixed, light response disappeared, eye inactivity. 4.Disappearance of brainstem reflexes, such as corneal reflex, cough reflex, swallowing reflex, ciliary reflex, open mouth reflex, head-eye reflex, etc., and no response to pressure on supraorbital neuralgia. 5.Blood pressure drops sharply and needs to rely on blood pressure-raising drugs to maintain. 6. Spinal reflexes such as tendon reflexes of upper and lower limbs, abdominal wall reflexes and metatarsal reflexes may sometimes still exist. After 6–12 hours of observation and repeated examination, no change in the above situation indicates brain death.