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Objective To explore the effect of inhibiting miR-155 on cardiomyocyte apoptosis and inflammation in myocardial ischemia-reperfusion (MI/R) model. Methods Myocardial cells of H9c2 rats were divided into four groups: blank control group, myocardial ischemia-reperfusion group (MI/R group), negative control group and miR-155 inhibitor group. The expressions of miR-155, NF-κB signaling pathway related genes and Bax, Bcl-2 mRNA were detected by RT-qPCR. The contents of IL-8 and TNF-α were detected by ELISA. Western blot was used to detect the expression of NF-κB signaling pathway related genes and Bax, Bcl-2 protein. Results Compared with the control group, the expression of miR-155 in MI/R group was significantly increased (P＜0.05) while the expression of miR-155 in miR-155 inhibitor group was significantly decreased (P＜0.05). In MI/R group, the apoptosis rate, the content of IL-8 and TNF-α, the protein and mRNA expression of Bax and NF-κB signal pathway were significantly higher than those in the control group, while the protein and mRNA expression of Bcl-2 were lower (P＜0.05). After inhibition the expression of miR-155, the apoptosis rate, the content of IL-8 and TNF-α, the protein and mRNA expression level of Bax and NF-κB signal pathway related gene were significantly decreased, while the protein and mRNA expression by Bcl-2 were increased (P＜0.05). Conclusions Inhibition of miR-155 expression can protect MI/R injury through inhibition of apoptosis and inflammation. The potential mechanism is the inhibition of the activation of NF-κB signaling pathway.