The normal range of high and low blood pressure is 90-140 mmHg for high pressure and 60-90 mmHg for low pressure. high pressure is systolic pressure and low pressure is diastolic pressure. high pressure greater than or equal to 140 mmHg and or low pressure greater than or equal to 90 mmHg is defined as hypertension. High pressure less than or equal to 90mmHg, low pressure less than 60mmHg, positioning hypotension. Both hypertension and hypotension are detrimental to the body. Hypertension is an independent risk factor for atherosclerosis, which can cause heart, brain and kidney atherosclerosis, and can cause cerebral infarction, myocardial infarction and renal insufficiency in severe cases. Hypotension can cause inadequate perfusion of the heart, brain and kidneys, and severe hypotension can also lead to cerebral infarction, myocardial infarction and ischemia of the kidneys. Normal people should try to keep their blood pressure within the normal range, and usually develop good living and eating habits and a balanced diet. Increase physical exercise appropriately, quit smoking and limit alcohol, eat more fresh vegetables and fruits, and maintain a good state of mind.