Aim To investigate the effects of leptin on the migration and proliferation of vascular smooth muscle cell(VSMC) in vitro. Methods The smooth muscle cells at passage of 4～6 were incubated with leptin in different concentrations(0,20,40,80,100,200 μg/L) for 24 hours,then modified Boyden's experiment was used to measure the effect of leptin on migration;MTT was used to measure the dosage-effect curve of leptin on the growth of VSMC;and flow cytometry(FCM) was used to measure the effect of leptin on the cell cyclin. Results The growth of VSMC was promoted with the concentration of leptin,and reached the maximum(OD:0.193±0.010) at 100 μg/L,so did the effect of leptin on the proliferation index of VSMC.Leptin can promote the migration of VSMC,and the number of migrated cell was promoted with the increase of leptin concentration. Conclusion Leptin can promote the migration and proliferation of VSMC in vitro,which explicits the effects of leptin in the atherosclerosis.