Objective:To investigate the influence of the composite chitosan/heparin coated membrane through a layer-by-layer self-assemble technique on stent thrombosis.Methods: The composite chitosan/heparin coated membrane,which was assembled through a layer-by-layer technique,was attached to the inside surface of cylinder made from 316L stainless steel flake to form membranes of different layers of chitosan/heparin.The activated partial thromboplastin time (APTT),prothrombin time (PT) and thrombin time (TT) of the whole blood samples of healthy controls were examined by clotting method; and the stability of its anticoagulation effect was also examined.The influence of the prepared composite chitosan/heparin coated membrane on coronary stent thrombosis was investigated using swine model of arteriovenous shunt thrombus.Results: The APTT and TT were significantly longer in the composite coated membrane group compared with those of 316L stainless steel group (P<0.01).Moreover,the prolongation of APTT and TT was correlated with the increase of coated layers.The anticoagulant function of chitosan/heparin coated membrane was stable for two weeks(P>0.05).The weight of thrombus was significantly lower in the coated stent group than that in 316L stainless steel group(P<0.001).Conclusion: The composite chitosan /heparin coated membrane made by layer-by-layer self-assemble has effective and stable anti-thrombotic function.