The co-culture of endothelial cells (ECs) with smooth muscle cells (SMCs) is an important method to study the biological characteristics of ECs and SMCs in vitro. but there are many difference of morphology and functions between in vitro and in vivo. It may because of no considering of the effects of blood flow shear stress. Therefore, we established the flow chamber system for the PET membrane co-culture model. through which we can obtain 0-40dyn/cm2 steady laminar flow shear stress. Using this system. the morphology of ECs co-cultured with SMCs were studied. The ECs alligned its long axis along the dire,direction of flow under 40dysn/cm2 for 24hours. The establishment of this flow chamber system provided a method to study the morphology and functions of ECs co-cultured with SMCs.