To observe whether inhibition of microRNA-29a can protect myocardial ischemia-reperfusion injury and to explore its specific mechanism. In vitro: H9C2 myocardial cells were used to establish myocardial ischemia model by hypoxia/reoxygenation, and microRNA-29a inhibitor was interfered. Annexin V/PI and flow cytometry were used to detect the effects of cell death. In vivo: C57 mice were used to establish ischemia reperfusion myocardial ischemia model. The rats were divided into normal control group and I/R group. Heart and serum were stained with HE to detect the pathological damage of heart. WB, Q-PCR, MDA and SOD kits and Elisa kit were used to detect the expression of miR-29a, SIRT1, pathways and inflammatory factors. The expression of serum enzymes HBDH, LDH, CK, CK-MB, IMA and inflammatory factors in patients with myocardial ischemia-reperfusion were up-regulated (P< 0.05). In I/R group, the expression of microRNA-29a was up-regulated, and SIRT1 down-regulated. The expression of SIRT1 in microRNA-29a inhibitor group was significantly higher than NC and mimics groups (P< 0.05). The expression of PGC-1a/Nrf2 was up-regulated, and eNOS up-regulated, iNOS down-regulated, MDA down-regulated. Oxidative stress of cardiac myocytes was down-regulated in the microRNA-29a inhibitor group compared with that in NC group (P<0.05). In group H/R, the expression of focal factor was higher than that in group control, and the rate of apoptosis was high. Mi-29a can regulate the expression of SIRT1, and then regulate NLRP3 and cell death pathway to protect myocardial ischemia-reperfusion injury. Mi-29a can be targeted for clinical treatment. In this study, we showed for the first time that miR-29a could improve myocardial I/R injury through inhibition of pyroptosis. The American Society for Pharmacology and Experimental Therapeutics.