Aim [WT5”BZ]To investigate the protective effect of Panax Notoginseng Saponins (PNS) on the cultured aortic smooth muscle cells (SMC). [WT5”HZ]Methods [WT5”BZ]In this study, cell culture technique was used in vitro. The protective effect of PNS on the proliferation of SMC was observed by measuring MTT metabolism and cell numbers and observing cell ultrastructure under TEM. [WT5”HZ]Results[WT5”BZ] The serum hyperlipidemia caused the increases in cell numbers and MTT metabolism of SMC. Under TEM, there are numerous rough endoplasmic reticulum and mitochondria and lipids in the cytoplasm of the cells cultured by serumof hyperlipidemia. The PNS can inhibit the proliferation of SMC dose dependently and can inhibit the proliferation of SMC stimulated by serumof hyperlipidemia significantly. [WT5”HZ]Conclusions[WT5”BZ] The PNS may prevent atherosclerosis and inhibit progression of the atheroslerotic lesions by interfering with the proliferation of arterial SMC.