The invention discloses application of irisin in the preparation of drugs for preventing myocardial ischemia reperfusion injuries. Experimental results show that irisin can decrease the myocardial infarction area caused by ischemia reperfusion, reduce the increase of the contents of lactate dehydrogenase (LDH), troponin (cTnI), creatine kinase (CK), and other myocardial enzyme markers caused by ischemia reperfusion, meanwhile reducing the inflammatory response, myocardial apoptosis, and oxidative stress response caused by myocardial ischemia reperfusion, promote peroxysome proliferator-activated receptor γ nuclear translocation, and inhibit nuclear transcription factor NF-κB nuclear translocation and accordingly decrease myocardial structure injuries and load increase caused by ischemia reperfusion. Therefore, irisin can be used for preventing and decreasing myocardial reperfusion injuries and has important clinical significance on the treatment of myocardial ischemia.