Background: Heart failure (HF) is a leading cause of death worldwide. Nuanxinkang (NXK) is an effective Chinese herbal formula used in treating HF, but its underlying potential mechanisms have not been fully elucidated. Purpose: To explore the protective activities of NXK in ischemia/reperfusion (IR)-induced HF through modulating the ratio of proinflammatory (M1) and anti-inflammatory (M2) macrophage populations and leading to the alleviation of inflammation. Materials and methods: In vivo, mice were subjected to myocardial IR to generate HF mouse models. Mice in the NXK group were treated with NXK for 28 days. Cardiac function was detected by echocardiography. Major lesions on mouse hearts were determined by hematoxylin-eosin (HE) staining, Masson staining, and TUNEL staining. Inflammatory cytokines were determined by enzyme-linked immunosorbent assay (ELISA) and qPCR examination. Flow cytometric analyses and qPCR examination were utilized for monitoring the temporal dynamics of macrophage infiltration following IR. In vitro, two polarized models were established by stimulating RAW264.7 cells with 200 ng/ml lipopolysaccharide (LPS) or 20 ng/ml interleukin-4 (IL-4). The RAW264.7 cells with nuclear factor-κB (NF-κB) overexpression was generated by transient transfection of NF-κB plasmids, and NXK intervention was conducted on this cell model to further clarify the involvement of NF-κB signaling in the NXK-mediated HF process. Results: In the present study, NXK was found to significantly contribute the cardiac function and ameliorate cardiac fibrosis and apoptosis after myocardial IR injury in vivo, which may be partially due to a decrease in inflammation. We therefore hypothesized that NXK reduced inflammatory damage by modulating subtypes of macrophages. And the results demonstrated that the percentage of proinflammatory macrophages infiltrated in the post-IR period was reduced with NXK treatment, and thereby blunting the wave of proinflammatory response and shifting the peak of the anti-inflammatory macrophage-mediated wound healing process towards an earlier time point. The further investigation showed that macrophage polarization was mediated by NXK through inhibiting the phosphorylation and the nuclear translocation of NF-κB. Besides, the phosphorylated IKKβ and IκBα, upstream mediators of the NF-κB pathway, also decreased by NXK. Moreover, the overexpression of NF-κB partially reversed the NXK-induced favorable activities; and successfully compensated the suppressive effect on inflammation and the phosphorylation of NF-κB. Conclusion: In conclude, our results demonstrated that NXK induced the cardioprotective effects against IR injury through a regulatory axis of IKKβ/IκBα/NF-κB-mediated macrophage polarization. The information gained from this study provide a possible natural strategy for anti-inflammatory treatment of HF. Keywords: Heart failure; Inflammatory response; Ischemia/reperfusion; Macrophage polarization; NF-κB.