Benign paroxysmal positional vertigo is a disease of the semicircular canal of the inner ear that is manifested primarily by transient vertiginous episodes during changes in head position. The disease is caused by the detachment of a degenerated otolith from the ellipsoidal sac of the inner ear vestibule into the semicircular canal and its constant movement in the semicircular canal in response to head position changes, resulting in a series of clinical manifestations. The clinical characteristics of vertigo in BPPV are: metastability, latency, transience, reciprocity, fatigue and characteristic nystagmus. The most common triggering position is when lying down, sitting up or turning over in bed, and it can also be triggered by rapid head lowering such as bending down or excessive head lifting such as fetching things from high places or drying clothes. 2. The latency period refers to the delay of vertigo attack for several seconds after head position change. 3. Transience refers to the fact that each vertigo attack lasts for several seconds or tens of seconds. 4. Interchangeability refers to the fact that vertigo attacks can be induced when moving in two opposite directions. 5. Fatigue refers to the fact that after changing the head position several times, the otoliths deposited in the semicircular canal are relatively dispersed, and when the otoliths move again, the pulling effect on the ridge of the potbelly is weakened, resulting in a decrease in the deviation of the ridge of the potbelly and a decrease in clinical vertigo symptoms. 6. The characteristic nystagmus is that the vertigo attack is often accompanied by the characteristic nystagmus which is consistent with the spatial position of the affected semicircular canals: groundward, rotational and upward nystagmus in the posterior semicircular canals, horizontal groundward or off-ground nystagmus in the horizontal semicircular canals, and downward nystagmus rotational groundward or rotational off-ground in the anterior semicircular canals. BPPV needs to be differentiated from the following diseases: 1. Meniere’s disease can appear when there is no change in head position, and the vertigo symptoms last for a long time, usually from minutes to hours, and are accompanied by other symptoms such as tinnitus, fluctuating hearing loss, and a feeling of fullness in the ear. 2.Vaginitis or vestibular neuronitis vertigo lasts longer, from several days to several weeks, and the vertigo symptoms can be aggravated by various head movements, often accompanied by horizontal spontaneous nystagmus, which is persistent and constant in direction, without transient vertigo and nystagmus attacks during evoked tests. 3.Migraine vertigo starts in adolescents, with recurrent attacks, each attack lasts for several hours to several days, brief vertigo attacks may occur and nystagmus attacks may occur during the trigger test. 4. Cervical vertigo was once widely diagnosed, but now the incidence is considered low. What’s more, whether in sitting or lying position, the vertigo attack caused by compression of vertebral artery after turning the neck will not disappear as long as the head position does not return to normal and the compression is not released, without transient characteristics. 5. Postural hypotension is more often seen when standing up from sitting or lying position, while vertigo attack does not occur when lying down, and it is often accompanied by black haze, and blood pressure check in standing position can make a clear diagnosis.