〔Abstract〕 Objective This study was to explore the protective effect and mechanism of caffeic acid on adriamycin-induced cardiomyocyte damage. Methods Adriamycin(ADM) is used to induce H9 c2 injury model of cardiomyocytes and to determine the best concentration of it. Then the injured H9 c2 were co-cultured with different concentrations of caffeic acid(CA) for 24 hours, and the optimal concentration of caffeic acid was selected. The H9 c2 were divided into model group(ADM), treatment group(ADM+CA) and blank control group(control). As shown, the survival rate of cardiomyocytes was measured by MTT method, and the morphology of H9 c2 was observed by HE. Then the levels of lactate dehydrogenase(LDH) and reactive oxygen species(ROS), changes in mitochondrial membrane potential and the activities of Na+-K+-ATPase and Ca2+-ATPase in H9 c2 were measured, as well as the expression of NF-κB-p65 were detected by Western blot. Results 2.0 μmol/L ADM and 4.0 μmol/L caffeic acid were selected for subsequent experiments. Compared with the control group, in the adriamycin-treated model group, the cardiomyocyte fiber arrangement was disordered, and the muscle fiber was deformed seriously; LDH and ROS levels were increased, mitochondrial membrane potential were increased, and Na+-K+-ATPase and Ca2+-ATPase activities were reduced. Compared with the model group, in the caffeic acid treatment group, myocardial cell muscle bundles were arranged neatly, LDH and ROS levels, and mitochondrial membrane potential were reduced(P<0. 05), while mitochondrial Na+-K+-ATP and Ca2+-ATPase activities were increased(P<0. 05), NF-κB-p65 protein expression was reduced(P<0. 05).Conclusion Caffeic acid can protect against oxidative stress, reduce mitochondrial membrane potential, increase the level of reactive oxygen species in H9 c2 cells, and participate in the protection of adriamycin-induced myocardial injury by regulating the NF-κB signaling pathway.