Objective To observe the changes of microRNA-97a and transforming growth factor β1 (TGF-β1) protein in the myocardium of spontaneously hypertensive rats (SHR). Methods 8 male spontaneously hypertensive(SHR)rats as SHR group, 8 male Wistar rats for control group, Arterial blood pressure was detected by a noninvasive blood pressure measurement and analysis system. 8 weeks after femoral artery,HE staining was used to observe the changes of morphology of the rat heart, the expression of miRNA-97a was checked by Real-time PCR method for detection of rat heart. Western blot was used to detect the TGF-β1, angiotensin II (Ang II) protein and type I collagen (Col I) and type III collagen (Col III) protein expression level. Results In SHR group, systolic blood pressure and diastolic blood pressure increased significantly, TGF-β1 protein and Col I and Col III protein expression levels increased significantly, miRNA-97a expression levels were significantly lower than that of control group (P<0.01). Real-time PCR results showed that the level of miRNA-97a expression in SHR group was (24.6+4.7)% in control group, the expression level of miRNA-97a in SHR group was negatively correlated with the expression of TGF-β1 (r=0.785, P<0.01) in group. Conclusion The level of miRNA-97a is down-regulated along with the up-regulation of TGF-β1 protein expression and collagen synthesis in the myocardial tissues of SHR. miRNA-97a and TGF-β1 may be involved in myocardial fibrosis in SHR.