An increasing number of studies have shown that noncoding RNAs are involved in cardiovascular diseases. Our study shows that the expression of microRNA-30a-3p (miR-30a-3p) in patients with arteriosclerosis obliterans (ASO) of the lower extremities is significantly decreased after endovascular treatment, but its role is unclear. This study aims to explore the role of microRNA-30a-3p in ASO and its related mechanisms. Immunofluorescence and in situ hybridization costaining indicated that microRNA-30a-3p mostly exists in vascular smooth muscle cells (VSMCs). Furthermore, after transfection into VSMCs, microRNA-30a-3p inhibited VSMC proliferation, migration and phenotype switching. In addition, luciferase reporter and western blot analyses indicated that ROCK2 (Rho-related spiral coil 2 containing protein kinase) is a microRNA-30a-3p target gene, and participates in the microRNA-30a-3p mediated cell inhibitory effect. At last, the rat carotid artery was infected by lentivirus after balloon injury, which increased microRNA-30a-3p levels and apparently suppressed the formation of neointima in vivo. Overall, exogenous introduction of microRNA-30a-3p, a noncoding RNA with unlimited potential, may be a new approach to treat ASO.