【Abstract】 Objective To investigate the effect of different exercise intensities on homocysteine in elderly patients with isolated systolic hypertension (ISH). Methods Eighty-five elderly ISH patients were randomly divided into a low intensity exercise group (hereinafter referred to as “low intensity group”, n=28), a moderate intensity exercise group (hereinafter referred to as “moderate intensity group”, n=27) and a natural activity group (hereinafter referred to as “control group”, n=30). Under the premise of achieving blood pressure control, the three groups were exercised according to the set exercise intensity. Hcy were measured as an evaluation index atonehour, 24 hours, 12 weeks and 24 weeks after exercise to observe the influence of different exercise intensity on Hcy in elderly ISH patients. Result At one hour after exercise, Hcy increased both in low and moderate intensity groups[(15.28±4.00)vs(15.49±3.94)， P＜ 0.05. (15.32±4.03) vs(15.61±3.76)， P ＜ 0.05]. At 24 hours after exercise, Hcy in low and moderate intensity groups recovered to baseline level[((15.28±4.00)vs(15.28±4.00)， P ＞ 0.05;(15.32±4.03)vs(15.33±4.02)， P ＞ 0.05]. After 12 weeks of exercise, Hcy in moderate intensity group decreased[(15.32±4.03)vs(13.45±2.85)， P ＜ 0.05]. After 24 weeks of exercise, Hcy in low and moderate intensity groups both decreased[(15.28±4.00)vs(13.61±2.58)， P＜ 0.05;(15.32±4.03) vs(13.00±2.56)， P ＜ 0.05], there was no statistical difference between the two groups. Conclusion Short-term acute exercise will increased the level of Hcy in elderly ISH patients, regardless of exercise intensity. However, the increase of Hcy after acute exercise was short-lived and recovered to baseline level within 24 hours. Moderate intensity of exercise for 12 weeks will decrease Hcys levels of elderly ISH patients, and both low and moderate intensity of exercises for 24 weeks will decrease Hcy levels of elderly ISH patients.