Atherosclerosis (AS), a severe disease characterized by an accumulation of lipids and fibers in the large arteries, is the most important contributor to ischemic stroke (IS). Although microRNAs (miRNAs) have been found in circulating blood, the role of miRNAs in the progression of AS remains unknown. In a previous study, we demonstrated that the spleen tyrosine kinase (Syk) gene plays a vital role in the process of IS. In the present study, we aimed to clarify whether the miRNAs targeting the Syk gene might slow the development of AS. Candidate miRNAs were screened in U937 and THP-1 cells via Bioinformatics analyses, RT-qPCR and dual-luciferase reporter assay. ApoE^−/− mice were used as an AS animal model. RAAV transfection was performed to identify the roles of Syk gene and miRNAs in the development of AS in ApoE^−/− mice. HE staining, Oil red O staining and immunohistochemistry were used to determine the mechanism of AS. RT-qPCR and western blotting were performed to determine the expressions of miRNAs and proteins, respectively. Over-expression of the Syk gene accelerated the development of AS. miR-377 effectively mediated the expression of the Syk gene in vitro and in vivo experiments. Further analysis indicated that over-expression of miR-377 partly alleviated the development of AS by down-regulating the expression of the Syk gene. This study identifies a novel role of miR-377 in AS via targeting Syk.