BACKGROUND: Mitochondrial dysfunction is an important pathological feature of chronic heart failure (CHF). Regulation of mitophagy can effectively maintain mitochondrial homeostasis and energy metabolism, thereby inhibiting the development of CHF. Nuanxinkang (NXK), a Chinese herbal compound preparation, has significant cardioprotective effects on CHF; however, its underlying mechanism on mitophagy has not been completely clarified. This research intended to investigate the mechanism of NXK in treating myocardial infarction (MI)-induced CHF. METHODS: The left anterior descending coronary artery (LAD) ligation surgery was performed to establish an MI-induced CHF model in male C57BL/6 mice. From 1 day after surgery, mice were given NXK (0.41, 0.82 or 1.65 g/kg/d), Perindopril (PDPL, 0.607 mg/kg/d), or an equivalent amount of sterile water by gavage for 28 continuous days. Then, mice were examined for cardiac function, myocardial fibrosis, cardiomyocyte apoptosis, mitochondrial structure and mitophagy levels of cardiomyocytes, etc. In addition, a hypoxic injury model was created using HL-1 cardiomyocytes from wild-type (WT) mice. HL-1 cells were pretreated with or without NXK-containing serum. Mitochondrial function and mitophagy levels were examined in HL-1 cells. RESULTS: In MI-induced CHF mice, cardiac dysfunction, severe cardiac remodeling, elevated levels of oxidative stress, reduced ATP levels, and inhibition of PINK1/Parkin-mediated mitophagy were observed. High-dose NXK treatment (1.65 g/kg/d) significantly improved myocardial energy metabolism, inhibited cardiac remodeling, improved cardiac function, and restored cardiac PINK1/Parkin-mediated mitophagy levels to some extent in MI mice. In vitro, elevated levels of mitochondrial reactive oxygen species (ROS) with impaired mitochondrial membrane potential (ΔΨm) were observed in hypoxic HL-1 cells. While NXK treatment significantly protected cardiomyocytes from hypoxia-induced mitochondrial dysfunction, which is consistent with the in vivo results. Further studies showed that NXK could increase PINK1/Parkin-mediated mitophagy levels in cardiomyocytes, which could be blocked by the mitophagy inhibitor Mdivi-1. CONCLUSION: In conclusion, NXK could prevent cardiac mitochondrial dysfunction and improve cardiac function against MI-induced CHF by promoting Pink1/Parkin-mediated mitophagy, which represents a very prospective strategy for the treatment of CHF.