The persistent vegetative state (PVS) was first proposed by Jennett and Plum in 1972. It refers to a state in which a person lacks conscious activity and language after a period of severe brain damage, but only retains unconscious posture adjustment and motor function. The vegetative state refers to a state in which the body can survive and develop, but lacks consciousness and thinking, and lacks the ability to perceive itself and the surrounding environment. The patient has a sleep-wake cycle, partially or completely preserves the functions of the hypothalamus and brainstem, but lacks any adaptive response and any functional thinking to receive and reflect information. The vegetative state can be temporary or persistent vegetative state (PVS). Some people believe that a vegetative state of more than 1 month or 1 year is called PVS, but it is generally believed that PVS must be diagnosed after > 1 year. The persistent vegetative state (PVS) is similar to coma and is easily confused with coma. Moreover, patients who are initially comatose can gradually develop into these states after varying periods of time. Once the patient has a sleep-wake cycle, true coma no longer exists. Differentiating between persistent vegetative state (PVS) and true coma is important for using appropriate treatment and determining prognosis.