There is mounting evidence that mesenchymal stem cell（MSC） help repair damage myocardial tissues primarily by means of secreting paracrine factors to inhibit cell apoptosis，inhibit myocardial fibrosis，promote angiogenesis and inhibit immune response. Recent studies have confirmed that these effects may be mainly mediated by exosomes. Exosomes are natural nano carriers secreted by cells，and contain cell-specific nucleic acids，proteins and lipids. Compared to liposome carriers，exosomes are low toxicity，less immunogenic，and can penetrate biological barriers. At present，many kinds of engineered exosomes targeting the heart have achieved good curative effects in animal models of myocardial infarction. This article reviews the mechanism research progress of MSC and exosomes derived from MSC in promoting the repair of damaged myocardium after myocardial infarction.