The rapid development of medical technology in today’s society has led to the preservation of life in patients who would otherwise die but have created a large number of patients with chronic disorders of consciousness, and scholars have tried to establish a uniform definition, classification, and diagnostic criteria for disorders of consciousness in order to promote scientific research in this field. The concept of persistent vegetative state (PVS) was first introduced by Jennett of Glasgow University, UK, and Plum of Cornell University, USA, in 1972, to describe the wakefulness of patients who are unaware of themselves and their surroundings. They have essentially intact brainstem and mesencephalon function and stable vital signs without artificial support. In 1982, Plum and Posner concluded that consciousness has a two-dimensional structure in clinical practice: wakefulness and awareness. The former is provided by the brainstem reticular formation and its thalamic projections (i.e., the brainstem reticular superior activating system), and the latter is provided primarily by the thalamus, cortex, and its white matter connections at this base. Damage to the brainstem reticular superior activating system leads to coma, whereas damage to the thalamus, cortex and its connecting fibers with the brainstem reticular formation functionally intact leads to a vegetative state. In 1994, after an evidence-based worldwide literature review, the Multi-Society Task Force (MSTF) published a report on the nomenclature, diagnosis, etiology, prognosis, and treatment of the vegetative state. In 1995, the American Society for Rehabilitation Medicine (ASRM) stated that a vegetative state of more than one month is called a persistent vegetative state, and a permanent vegetative state (PVS) of one year after traumatic brain damage and three months after non-traumatic brain damage, which means that the patient has little chance of regaining consciousness. This means that the patient has little chance of regaining consciousness. Due to differences in opinion between the American Academy of Neurology and the Society of Rehabilitation Medicine, the Aspen Neurobehavioral Collaborative Group, composed of representatives from neurology, neurosurgery, and neurorehabilitation, was responsible for developing a consensus statement on the vegetative state in 1997 [3]. The statement used the term vegetative state (VS) as a uniform designation, a name that already covered the previous decortical state and inactive muteness, while Persistent and permanent were only used in prognostic descriptions. The statement also introduced the concept of minimally conscious state (MCS) to describe the state of consciousness in patients who are affirmative but not consistently compliant with instructions. To unify clinical and research guidance on VS, the Royal College of Physicians in the United Kingdom, in conjunction with the University of Edinburgh and Glasgow University, published guidelines on diagnosis and treatment in 2003, and the JFK Medical Center in the United States published guidelines on VS and MCS in 2004 [4, 5]. Currently, from the perspective of clinical diagnosis and differentiation, five categories of disorders of consciousness can be distinguished, including brain death, coma VS, MCS, and atresia syndrome. Since the establishment of the concepts of VS and MCS, the scales designed for the assessment of disorders of consciousness have become more detailed and precise, thus allowing better observation of changes in the condition and identification of the above-mentioned disorders of consciousness. The complexity of consciousness impairment makes it difficult to assess the patient’s level of awareness. The Glasgow Coma Scale (GCS), which was used earlier to assess coma after acute brain injury, is simple and effective, but is too crude for VS and MCS. Because of the high rate of misdiagnosis in both, accurate assessment is even more important. Systematic and careful examination and prolonged bedside observation are necessary, while it is particularly important to distinguish whether the patient’s response is a reflexive response to the stimulus itself or comes from the exact ability to know. Over the past few decades, numerous scales have been developed to assess impairment of consciousness, among which the CRS-R has been used effectively for VS and MCS, the WHIM can be used without special training, the SMART is designed for VS and can be used both for assessment and rehabilitation, and the DOCS is highly accurate in assessing the level of consciousness.