The normal range of blood pressure for a 48 year old should be 90~139mmHg systolic and 60~89mmHg diastolic. Blood pressure usually refers to the arterial blood pressure of the body circulation, which is a very important vital sign, and the normal range should be systolic blood pressure 90~139mmHg, diastolic blood pressure 60~89mmHg. It can be used for the diagnosis of many diseases and the monitoring of critically ill patients. Hypertension is diagnosed when systolic blood pressure ≥140mmHg and/or diastolic blood pressure ≥90mmHg is measured on three occasions not on the same day without the use of antihypertensive drugs. Correspondingly, a systolic blood pressure of less than 90 mmHg and/or a diastolic blood pressure of <60 mmHg is considered hypotension and needs to be analyzed on a case-by-case basis. If your blood pressure is too high or too low, you should go to a regular hospital to get a clear diagnosis and control your blood pressure as soon as possible.