Aim To observe whether mechanical stretch stress (SS) induces the proliferation and migration of mouse vascular smooth muscle cells (VSMC) through PKCδ activation, and to further explore the effect and mechanism of berberine (BBR) on the proliferation and migration of VSMC. Methods Mouse VSMC in vitro were divided into six groups:negative control group (NC), berberine group (BBR), PKCδ inhibitor Sotrastaurin group (Sotras), SS group, SS+BBR group and SS+Sotras group. The cultured VSMC in each group,which were pretreated with BBR or Sotrastaurin or ddH₂O for 1h, followed by SS (10% tensile strength) for different time or no treatment for control, were collected for the detection of PKCδ phosphorylation, proliferation and migration by Western blot, immunofluorescence and scratch assay respectively. Results Immunofluorescence and cell scratch test results showed that compared with NC group, SS stimulation significantly increased Ki67 positive level in VSMC by 469%(P＜0.05, n＝3), and reduced scratch width by 54.9%(P＜0.05, n＝3),while BBR and Sotrastaurin could significantly inhibit the changes caused by SS, Ki67 positive level decreased by 66.9% and 80.2%(P＜0.05, n＝3), and scratch width increased by 79.4% and 120.1%(P＜0.05, n＝3)compared with SS group, respectively. Meanwhile, Western blot results showed that SS stimulation induced a time-dependent increase in PKCδ phosphorylation compared with NC group, with the most significant increase of 97.5%(P＜0.05,n＝3) at 30 min, which also inhibited by berberine in a concentration-dependent manner, and the effect was the most significant at 200 μmol/L, with a decrease of about 37.6% (P＜0.05, n＝3). Conclusion Berberine inhibits SS-induced vascular smooth muscle cell proliferation and migration by inhibiting PKCδ phosphorylation.