〔Abstract〕 Objective To study the protective effect of asiaticoside(AS) on Isoproterenol Hydrochloride(ISO)-induced myocardial injury in mice. Methods Sixty male C57BL/6 mice were randomly divided into blank control(CON) group, model group [ISO,ISO 10/(kg·d)], Low dose group [ISO+AS-L,ISO 10 mg/(kg·d)+AS 5 mg/(kg·d)], Medium dose group [ISO+AS-M, ISO 10 mg/(kg·d)+AS 10 mg/(kg·d)], High dose group [ISO+AS-H, ISO 10 mg/(kg·d)+AS 20 mg/(kg·d)]. Heart mass ratio was counted; changes were observed in electrocardiogram; Enzyme linked immunosorbent assay(ELISA) was used to detect the levels of interleukin(IL)-1β and cardiac troponin T(cTn-T) in serum; Masson staining was used to observe the fibrosis of mouse myocardial tissue; Western blot was used to detect the ratio of Bax and Bcl-2 protein expression levels(Bax/Bcl-2) and the expression levels of Caspase-3 and NLRP3 proteins in myocardial tissue; real-time quantitative polymerase chain reaction(qPCR) was used to detect the mRNA expression levels ofANP,BNP,β-MHC,TNF-α, IL-6, Type Ⅰ collagen(COLⅠ), and Type Ⅲ collagen(COLⅢ). Results Compared with the CON group, the ISO group had an elevated heart-to-mass ratio(P<0.01), a lower heart rate(P<0.05), a prolonged QT interval(P<0.05), elevated expression of myocardial injury markers cTn-T,ANP,BNP, andβ-MHC(P<0.01); increased expression of IL-1β in the serum(P<0.01), increased expression ofTNF-αin the cardiac tissue and increasedIL-6expression(P<0.001), and NLRP3 protein expression was elevated(P<0.05); myocardium showed a large number of collagen fibers bluish staining(P<0.001),COLⅠ,COLⅢmRNA expression levels increased(P<0.001), and Bax/Bcl-2 ratio(P<0.001) and Caspase-3 expression were significantly elevated(P<0.05). Compared with ISO group, heart-to-mass ratio of mice in ISO+AS-L and ISO+AS-M groups decreased(P<0.05), heart rate increased, QT interval was shortened, cTn-T, ANP, BNP and β-MHC decreased(P<0.001), myocardial collagen fiber blue-staining decreased(P<0.01). The mRNA expression levels ofCOLⅠandCOLⅢdecreased(P<0.05). The expression levels of IL-1β and TNF-α decreased(P<0.01). NLRP3, Caspase-3 protein expression and Bax/Bcl-2 ratio decreased(P<0.05). The expression level ofIL-6in ISO+AS-M group decreased(P<0.01). The expression levels ofANP,BNP, andTNF-αmRNA expression were reduced in the ISO+AS-H group(P<0.001); the degree of myocardial fibrosis was improved(P<0.05), and the expression levels ofCOLⅠandCOLⅢmRNA were reduced(P<0.05). Conclusion AS has a protective effect against ISO-induced myocardial injury in mice by ameliorating cardiac fibrosis, inhibiting cardiomyocyte apoptosis and attenuating myocardial tissue inflammatory response.