Objective To investigate the role and related mechanism of the soluble guanylate cyclase (sGC)cGMP-protein kinase G (PKG) signaling pathway in the amelioration of isoproterenol (ISO)-induced cardiac hypertrophy in mice by aqueous extract of Curcuma kwangsiensis root tubers (GYJS). Methods 72 KM male mice were divided randomly into 6 groups: normal, model, propranolol control (40 mg/kg), and GYJS low- (1 g/kg), medium-(2 g/kg), and high-dose (4 g/kg) groups. Mice in the experimental groups were injected subcutaneously with ISO 10 mg/kg on days 1~3 and ISO 5 mg/kg on days 4~14 to establish a mouse cardiac hypertrophy model. 4h after each subcutaneous injection of ISO, the mice in each group were administered the corresponding drugs orally for a dosing cycle of 14 days. The hearts were then removed and whole heart and left ventricle weight were measured. Myocardial tissue pathology was observed using hematoxylin and eosin and Masson staining, and sGC subunit beta-1 (GUCY1B3) and transforming growth factor (TGF β1) were detected by immunohistochemistry. Serum lactate dehydrogenase (LDH), creatine kinase (CK), and Nitric Oxide (NO), and myocardial superoxide dismutase (SOD) activity and malondialdehyde (MDA) content were measured using respective kits. Serum cGMP was detected by enzyme-linked immunosorbent assay and quantitative reverse transcription PCR (RT-qPCR), and atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), GUCY1B3, PKG Ⅰ, and phosphodiesterase (PDE) 5A mRNA expression levels were also determined by RT-qPCR. Results Compared with the model group, whole heart and left ventricle weights were significantly reduced in mice treated with propranolol or GYJS (P<0.001 or P<0.0001) and myocardial hypertrophy and myocardial fibrosis were significantly reversed. All the treatments significantly elevated myocardial expression of GUCY1B3 (P<0.05 or P<0.01) and significantly reduced expression of TGF-β1 (P<0.05 or P<0.01). The myocardial damage markers LDH and CK were significantly reduced (P<0.05 or P<0.01) while NO and cGMP were significantly elevated (P<0.05 or P<0.01), the myocardial oxidative stress indicator MDA was significantly reduced (P<0.05 or P<0.01) and SOD activity was significantly increased (P<0.05 or P<0.01). mRNA levels of the myocardial hypertrophy markers ANP, BNP, and PDE5A were significantly reduced (P<0.05, P<0.01, or P<0.001) and the mRNA levels of GUCY1B3 and PKGⅠ were significantly increased (P<0.01 or P<0.001). Conclusions GYJS may improve cardiac hypertrophy by modulating the sGC-cGMP-PKG signaling pathway.