Ischemic heart disease is a major cause of mortality and disability worldwide. Salvianolic acid B (Sal B) is one of the main water‑soluble components of Salvia miltiorrhiza Bge. Numerous studies have demonstrated that Sal B could exert significant anti‑inflammatory and cardiovascular protective effects; however, the underlying mechanisms remain unclear. To elucidate the association between myocardial ischemia and inflammation, and to develop effective protective drugs, a rat model of myocardial ischemia was induced using isoproterenol (ISO) and an inflammation model in H9C2 cells was induced with lipopolysaccharide + adenosine triphosphate. Both of these models were treated with different concentrations of Sal B (5, 10 and 15 mg/kg in vivo; 1, 5 and 25 µM in vitro). In vivo, the serum levels of creatine kinase isoenzyme MB, glutamic oxaloacetic transaminase and IL‑1β, the cardiac function and the mRNA expression levels of NLR family pyrin domain‑containing 3 (NLRP3) inflammasome components were evaluated using ELISAs, an electrocardiogram, hematoxylin and eosin staining and reverse transcription‑quantitative PCR, respectively. The results demonstrated that treatment with Sal B markedly alleviated the acute myocardial ischemic injury induced by hypodermic injection of ISO in rats. In vitro, the results of reactive oxygen species (ROS) detection, JC‑1 staining, western blotting and TUNEL assays showed that Sal B treatment significantly inhibited intracellular ROS production, increased the mitochondrial membrane potential, regulated the expression of mitophagy‑related proteins, inhibited the activation of the NLRP3 inflammasome and inhibited apoptosis in H9C2 cells. In conclusion, these findings indicated that Sal B exerted protective effects against myocardial ischemic injury by promoting mitophagy and maintaining mitochondrial function.