MicroRNA(miR)have been considered as the important regulators in both physiological and disease contexts, among which miR-34a has drawn great attention as its multiple functions in cardiovascular disease. It is reported that miR-34a is either upregulated or downregulated in atherosclerotic cardiovascular diseases, etc. This article reviews both the roles and mechanisms of miR-34a in cardiovascular diseases, aiming to provide new ideas for further researches on biomarkers and treatment target of cardiovascular disease.