Qing Gan Zi Shen Decoction (QGZS) is a traditional Chinese formula. It has been extensively used for decades in the treatment of hypertension combined with metabolic diseases, but its cardioprotective effects and underlying mechanisms are poorly understood.To explore the cardioprotective effects and potential mechanisms of QGZS in an animal model of obese hypertension.In this study, spontaneously hypertensive rats (SHRs) were utilized as an animal model to examine the effects of a high-fat diet and two concentrations of QGZS. Echocardiography, hematoxylin eosin (H&E) staining, and wheat germ agglutinin (WGA) staining were employed to assess the cardiac structure and function of the SHRs throughout a 16-week therapy period. Furthermore, Western blotting (WB) and immunofluorescence (IF) were employed to identify the levels of Nrf2 expression in the mitochondria, cytoplasm, and nucleus of the myocardium. Additionally, transmission electron microscopy and enzyme-linked immunosorbent assay (ELISA) were utilized to measure mitochondrial morphology and pro-inflammatory cytokine levels, respectively. Furthermore, Western blotting (WB), immunohistochemistry (IHC), and immunofluorescence (IF) techniques were employed to quantify the levels of marker proteins associated with myocardial fibrosis, cardiac inflammation, oxidative stress, and mitochondrial dysfunction.QGZS inhibited weight gain and depressed systolic and mean arterial pressures in high-fat-fed SHRs. Echocardiographic results demonstrated that QGZS prevented the increase in left ventricular mass, restricted the growth of left ventricular diameter, and improved ejection fraction (EF), fractional shortening (FS), and the ratio of early diastolic peak velocity of transmitral flow (E) to late diastolic peak velocity (A) in high-fat-fed SHRs. This suggested that QGZS prevented ventricular remodeling and protected cardiac systolic and diastolic functions. H&E and WGA staining showed that QGZS improved cardiomyocyte disorders and restricted cardiomyocyte hypertrophy. The underlying mechanisms, QGZS attenuated the oxidative stress state, including reducing the generation of reactive oxygen species (ROS) in the myocardium, revitalizing the antioxidant enzyme system, and protecting mitochondrial function. Moreover, QGZS alleviated the pro-inflammatory state in high-fat-fed SHRs. What's more, QGZS significantly increased the expression level of Nrf2 in nuclei and mitochondria in rat heart tissues, exerting a proximate Nrf2 agonist effect.QGZS exerted cardioprotective effects, in part due to its increasing expression of Nrf2 protein in the heart, which promoted Nrf2 nuclear expression.