This study mainly analyzed the protective effect of Qutan Huoxue Decoction on myocardial hypertrophy and fibrosis in spontaneously hypertensive rats(SHRs) and investigated whether the protective effect of Qutan Huoxue Decoction on myocardial hypertrophy and fibrosis in SHRs is related to transforming growth factor-β1(TGF-β1)/Smad pathway.It also explored the mechanism of the protective effect of Qutan Huoxue Decoction on myocardial hypertrophy and fibrosis in rats.Methods:Twenty SHRs were randomly divided into four groups：model group，low-dose group of Qutan Huoxue Decoction，high-dose group of Qutan Huoxue Decoction，and AMST group(Omesartan).Five Wistar rats were set as the normal control group.After four weeks of intragastric administration，the effects of Qutan Huoxue Decoction on blood pressure and left ventricular mass index(LVMI) of SHRs were observed，and the effects of Qutan Huoxue Decoction on myocardial cell morphology，endothelin-1(ET-1)，angiotensin Ⅱ(AngⅡ)，and nitric oxide(NO) content were studied by using hematoxylin-eosin(HE) staining，radioimmunoassay，nitric acid reductase，reverse transcription-polymerase chain reaction(RT-PCR)，and immunohistochemical method.The mRNA level of TGF-β1 and the expression of Smad2/3 and Smad7 proteins in myocardial tissue were detected.Results:Qutan Huoxue Decoction could significantly reduce blood pressure and LVMI of SHRs，improve myocardial cell morphology of SHRs，reduce plasma ET-1 and AngⅡ content of SHRs，and increase serum NO level of SHRs.Qutan Huoxue Decoction could reduce TGF-β1 mRNA level and Smad2/3 protein expression of SHRs and increase the expression of Smad7 protein.Conclusion:Qutan Huoxue Decoction can reduce myocardial hypertrophy and fibrosis and improve the cardiac function of SHRs，and the mechanism of this protective effect may be related to the inhibition of the TGF-β1/Smad signaling pathway.