Sudden dizziness is firstly considered to be caused by cerebrovascular disease. Clinically, posterior circulation ischemia is common, mainly referring to the slowing down of blood flow or blockage of both vertebral and basilar arteries, and the patient may experience symptoms of cerebellar or brainstem ischemia. It manifests as sudden dizziness, nausea, vomiting, numbness and weakness of the limbs or walking obliquely, which can be investigated by head CT, MRI and intracranial segmental vascular ultrasound, and treated with symptomatic therapy such as antiplatelet aggregation, blood circulation and improvement of circulation. Secondly, sudden dizziness can also be seen as peripheral vertigo, which is a problem in the extracranial segment of the vestibular nerve. The most common clinical cases are Meniere’s syndrome, vestibular neuronitis, and vestibular paroxysm. In general, patients may experience dizziness, which may be accompanied by ear stuffiness and ear swelling, etc. Treatment may include vestibular depressants, such as betahistine mesylate, as well as drugs to improve microcirculation.