Abstract: Tumor capillary blood vessel is much different from vessel in normal tissues.Based on microfluidic chip of normal tissue vessels which was prepared in this laberatory,a novel tumor capillary model preparation has been made using microfabrication technology.The model consists of（1） a microchannel with 24 mm in length,50 μm in width and 40 μm in depth,（2） a microchamber linked to a microchannel by micro gaps.The microchannel was expanded at three sites in the middle part to mimic the irregular structure of tumor capillary.After the microchannel being transfused with human umbilical vein endothelial cells,the chip was cultured for 10 d to obtain an integrated cell barrier.Permeability has been achieved after 24 h induction for cell migration by adjusting the height of culture medium in pipette tip of inlet and outlet.The permeability of microfluidic chip well mimicked the characteristics of tumor blood vessels.The chip can respond just like in vivo to histamine and metalloprotease-2 which can induce high permeability.In present study,this microfluidic chip has been used to measure the effect of procyanidins and irinotecan,a clinical medicine for curing cancers,on permeability.The result showed that procyanidins at 0.1,1 and 2 μg/mL can inhibit the permeability.All these data proved the prepared microfluidic chip has the primary function for permeability assay.