Objective To investigate whether calcitonin generelated peptide (CGRP) can influence the proliferation and phenotypic modulation of vascular smooth muscle cells(VSMCs), and what is the relationship between them. Methods Vascular smooth muscle cells(VSMCs) were cultured respectively with rat aorta cultivated for 8 days in vitro and with normal aorta (not culture) through the explantattached method, and CGRP was added into the culture medium of the experimental groups. The proliferation of cells was labeled by 5bromodeoxyuridine (5BrdU) with immunocytochemical method, and the mRNA expression of hypertensionrelated gene1 (HRG-1) and smooth muscle 22 alpha (SM22α) were determined by RT-PCR. Results The proliferating cells labeled by BrDU from the aorta cultured for 8 days in vitro were increased notablly and the mRNA expression of HRG1 and SM22α were decreased. While the VSMCs were cultured in the culture medium containing CGRP, the proliferous cells labeled by BrdU were obviously decreased and the mRNA expression of HRG-1 and SM22α were significantly increased. Conclusion It is showed that CGRP could inhibit the proliferation of VSMCs and change the phenotype of