Nowadays, the incidence of stroke in China has reached 1.6‰, and this disease has became a primary cause of death in China. One of its major risk factors is hypertension. As shown in the researches, the risk of stroke grows remarkably when the blood pressure increases and there exists a log-linear relationship between them. Systolic pressure and diastolic pressure relate to the risk of stroke independently. Systolic pressure decreasing 10mmHg will reduce the stroke risk by 31% and decrease of 1~3mmHg will reduce the stroke risk by 20~30%. As to diastolic pressure, 5mmHg decrease of it will reduce the stroke risk by 34% and 10mmHg decrease of it will reduce the stroke risk by 56%. In addition, patients with isolated systolic hypertension (SPB≥160mmHg, DPB≤90mmHg) or critical isolated systolic hypertension (SPB=140~159mmHg, DPB< 90mmHg) will suffer a higher risk of stroke than people with normal blood pressure. The ACC has already revised its Hypertension Management Guidelines of standard of diagnosis for hypertension and timing of starting medical treatment in hypertensive patients.Because more and more reseaches shown that people with blood pressure between 120-139/80-89mmHg have higher risk of ASCVSD compared to those with blood pressure lower than 120/80mmHg; However, in China, the diagnostic criteria for hypertension has not been revised yet. Therefore, we still have blind spot in treating such patients who suffer from borderline systolic hypertension at 130~140 mmHg of blood pressure with or without ASCVD or those with the first stage hypertension but refusing to take anti-hypertension drugs. What is more, most of them are middle-aged adults, once they have stroke, it would lead terrible and costly consequences to both their family and the society. Thus, it is necessary to explore new non-pharmacological methods to control blood pressure for reducing the risk of stroke.

There already have had some researchers found the phenomenon of lowing blood pressure among heart failure patients and pre-hypertensive individuals after a long-term of ischemic conditioning therapy. However, there's still lack of specific clinical trials carried out to confirm itspotential treatment effect of lowing blood pressure.

The investigators designed this randomized, doubleblind, controlled clinical trial to examine (1) whether RIC has a beneficial effect on blood pressure; (2) whether RIC exert its protection effect through immunological regulation. There are 2 arms in this trial: One arm is RIC treatment, the other one is sham RIC treatment. Blood pressure will be measured by ambulatory blood pressure monitoring before and after the treatment to evaluate its exact effect on BP. Also, circulatory immunological factors will be tested before and after the treatment to illustate whether immunological regulation involved in the process.

Inclusion Criteria:

1. ABPM measures systolic and diastolic blood pressure within the range of 125-145/75-90mmHg;
2. Essential hypertension;
3. without use anti-hypertensive drugs;
4. Written consent was obtained from the subject.

Exclusion Criteria:

1. patients already have had anti-hypertensive drugs;
2. patiets with diabetes mellitus and have a poor blood glucose control;
3. patients with atrial fibrillation or other kinds of arrhythmia;

7. unstable general condition; 8.Subject participating in a study involving other drug or device trial study; 9. patients that investigators think is not suitable.