Suddenly feel weak legs and dizziness are mainly due to the following reasons: First, for young patients who suddenly feel weak legs and dizziness, ask the patient if they have had long-term ambulatory work recently, or if they have had their neck in a posture for too long, if long-term ambulatory work or neck posture is not correct it is easy to cause cervical spondylosis, causing insufficient blood supply to the vertebral artery type, suddenly feel weak legs and dizziness. Second, if a middle-aged or elderly patient with a history of diabetes, hypertension, coronary heart disease, etc., suddenly appears weak legs and dizziness, consider that the patient may have acute cerebrovascular disease of the posterior circulation, such as cerebral infarction or cerebral hemorrhage, then need to go to the hospital to do a cranial magnetic resonance examination to clarify the diagnosis. Third, sudden feeling of leg weakness and dizziness, ask the patient if he usually has low blood pressure, if he is a long-term hypotensive patient, it is easy to have postural hypotension and dizziness and leg weakness when there is a sudden change in position.