Systolic blood pressure 120mmHg diastolic blood pressure 55mmHg can be temporarily observed if there are no symptoms, if there are related symptoms, pay attention to find the cause. Systolic blood pressure 120mmHg is within the normal range, while the normal diastolic blood pressure level is between 60~90mmHg, 55mmHg is slightly lower than the normal value, the patient may not have any clinical manifestations, which can be seen in the elderly patients, atherosclerosis is the cause of low diastolic blood pressure, most of the patients do not need special treatment. Low diastolic blood pressure, such as related symptoms, such as dizziness, chest tightness, etc., should pay attention to improve the relevant examination, can be carried out cardiac ultrasound examination, to understand whether the patient exists in the aortic valve closure insufficiency, the condition is serious need to carry out valve replacement therapy. Low diastolic blood pressure does not require special treatment, but we should pay attention to strengthen the monitoring, and if there are symptoms, we should go to the hospital in time.