For a 70-year-old, the normal range of blood pressure should be 90-139mmHg systolic and 60-89mmHg diastolic. if the blood pressure is less than 90/60mmHg for a long period of time, it can be diagnosed as low blood pressure. 1. Before measuring blood pressure, rest sufficiently, and avoid emotional fluctuations and prohibit smoking before measuring blood pressure. For the accuracy of the measurement results, three consecutive measurements should be taken and the average value should be taken. 2. For physiological hypotension, it can be regulated by adjusting the diet, such as proper supplementation of salt and water. 3. If the hypotension is caused by cardiomyopathy, pericarditis, severe aortic stenosis, etc., the specific cause of the disease needs to be removed to correct the low blood pressure. If the blood pressure is persistently low, it may cause serious adverse consequences and requires prompt medical attention and standardized treatment under the guidance of a doctor.