Abstract: TiO2 thin films were deposited on nanocrystalline titanium and coarse-grained commercial pure titanium by DC reactive magnetron sputtering.The structure of the films was analyzed by XRD.The anti-coagulant properties of different thin films were investigated through dynamic clotting time and platelet adhesion in vitro respectively.The results show that thin films on nanocrystalline titanium had finer,more uniform and compact grains than those on coarse-grained commercial pure titanium.The TiO2 thin films structure were composed of rutile and anatase.Nanocrystallization of Ti substrate could improve the anti-coagulant properties of itself and TiO2 thin films.