Death is the end of everyone’s life. If someone asks you how to determine whether a person is dead, perhaps the first thing you would think of is that the heart has stopped beating and there is no breathing. Indeed, the current death refers to the permanent cessation of heartbeat and respiration, which cannot be recovered by active resuscitation. Such a standard is also accepted and recognized by all sectors of society as well as the public. However, in fact, the criteria for determining death are currently not clearly defined in our laws. In the opinion of the medical profession, brain death is the most scientific criterion for determining death. So, what is brain death? It refers to the total and permanent cessation of the functions of the two hemispheres of the brain and the brainstem. In 2003, China has formulated the criteria for determining “brain death”. 1. irreversible coma and brain unresponsiveness; 2. disappearance of brain waves; 3. respiratory arrest, unable to resume spontaneous breathing after more than 15 minutes of artificial respiration; 4. disappearance of cranial nerve reflexes (such as pupillary reflex, corneal reflex, swallowing reflex, etc.), but spinal reflexes can exist; 5. dilated and fixed pupils; 6. complete cessation of cerebral circulation (as shown by cerebral angiography); body temperature above 35℃; no History of drug and poison poisoning (e.g., overdose of sleeping and sedative drugs). Among these 6 points, the first two points mainly reflect the loss of brain function in both hemispheres; points 3 to 5 mainly reflect the loss of brainstem function; point 6 is set to further confirm and exclude some special accidents. Such determination criteria tell us that declaring brain death must be done with great caution, and usually requires 2 to 3 repeated examinations within 24 hours before final confirmation. It can be said that the introduction of the concept of brain death is a major advance in human understanding of death. On the one hand, medical advances have allowed us to realize that while an individual who has experienced brain death can rely on expensive life support systems to maintain a heartbeat and breathing for a period of time, it is costly and pointless because the individual has absolutely no chance of recovery. With that said, some may think of another condition – vegetative. Brain death is different from vegetative state. Although the functions of both hemispheres of the brain are also completely as well as permanently stopped in a vegetative person, the brainstem functions are still preserved, and the higher centers of heartbeat and respiration are in the brainstem, so a vegetative person has an autonomous heartbeat and respiration and does not need additional life support systems to maintain a long-term, unconscious life in a vegetative state as long as there is proper nutritional supply and life care. Moreover, there is no reliable method to determine the irreversible and permanent cessation of function of both hemispheres of the brain in a patient in a vegetative state, while in reality, there have been cases of patients who survived for several years in a vegetative state and finally awakened. On the other hand, the use of brain death as a criterion for death also allows the use of organs that still have normal structure and function for transplantation to save other lives that are at risk. For example, in the highly publicized case of the “Thousand Mile Heart Rescue Boy”, a 21-year-old boy from Guangxi was determined to be brain dead by medical experts, but his family fully understood and chose to stop treatment and donate his organs according to the brain death criteria, and his hospital agreed and supported him. His heart continues to beat inside the chest of a 12-year-old boy in Beijing. Although the use of “brain death” to determine the end of a person’s life is still ethically and legally controversial, it is believed that with the development of medical science and the advancement of human thought, one day the brain death criteria will be adopted by legislation.