Abstract: Objective To explore the effects of aerobic treadmill exercise on blood pressure and intestinal flora of spontaneously hypertensive rats (SHR). Methods Twelve male 8-week-old SHR were randomly divided into SHR group and SHR exercise group, with 6 in each group, and 6 male Wistar Kyoto (WKY) rats of the same age were set as the normal blood pressure control group. Rats in the normal blood pressure control group and SHR group were placed on a stationary treadmill for 60 min/day,5 days/week, while the rats in the SHR exercise group underwent continuous 8 weeks of treadmill exercise (speed 18-20 m/min, treadmill slope 0°, 60 min/day, 5 days/week). Systolic and diastolic blood pressure of the rat tail artery were measured on the day before the experiment and at week 2, 4, 6 and 8 of the experiment. Fecal samples were collected from rats in each group 8 weeks after the experiment for 16S rDNA high-throughput sequencing to analyze the composition and diversity of intestinal flora. Results Compared with the SHR group, the systolic blood pressure and diastolic blood pressure of the SHR exercise group rats significantly decreased at week 8 (P<0.05). There was no significant difference in α diversity between SHR and SHR exercise group (P>0.05), and the flora structure in SHR exercise group was more similar to that of the normal blood pressure control group. Compared with the SHR group, in the SHR exercise group, at the phylum level, the relative abundance of Elusimicrobia increased (P<0.05), and the relative abundance of Spirochaetes decreased (P<0.05); and at the genus level, the relative abundance of beneficial bacterial genera such as Elusimicrobium and Ruminococcaceae UCG-009 increased (P<0.05). The genera Elusimicrobium, Marvinbryantia, Negativibacillus, Ruminococcus_1 and Dubosiella, which were negatively correlated with systolic blood pressure, were significantly increased (P<0.05), and ASF356, which was positively correlated with systolic blood pressure, showed a significant decrease after treadmill exercise intervention (P<0.05). Conclusion Treadmill exercise can reshape the composition of intestinal flora in SHR rats, enrich the beneficial genera and reduce the harmful bacterial abundance in the intestinal tract, restore intestinal microecological balance, thus exerting antihypertensive effects.