Abstract: Objective To observe the inhibitory effect of HO-1 and rapamycin on PDGF-BB-induced phenotype transformation in vascular smooth muscle cells（VSMC）of rats. Methods Phenotype transformation was induced by PDGF-BB in primary rat aorta VSMC.Expression of HO-1 was induced with different doses of PDGF-BB.The cells were cultured with HO-1 and rapamycin for 24h. Results Twenty-four hours after phenotype transformation in VSMC of rats was induced with PDGF-BB,the expression of SM-α-actin was down-regulated while the expression of PCNA was up-regulated.Hemin-induced HO-1 suppressed PDGF-BB-induced expression of VSMC in a dose-dependent manner.Low dose rapamycin could inhibit PDGF-induced phenotype transformation in VSMC. Conclusion PDGF-BB subtype can promote the transformation of contraction phenotype to synthetic phenotype in VSMC.Hemin-induced HO-1 can inhibit PDGF-BB-induced phenotypic transformation in VSMC in a dose-dependent manner.