Epoxidized castor oil-based polyurethane were synthesized with epoxidized castor oil (ECO) and isophorone diisocyanate (IPDI) as the main raw materials. Epoxidized castor oil-based polyurethane (ECOPU) films were impregnated in different concentrations of chitosan (CS) solution containing acetic acid to prepare CS/ECOPU composite film. The structure and morphologies of the film have been characterized by means of mass change test, infrared spectroscopy, and optical polarization microscope. The recalcification time and dynamic blood-clotting tests were used to characterize the blood compatibility of CS/ECOPU composition film. The result showed that CS has been grafted onto the surface of ECOPU film. The material had good blood compatibility, and can be used as biomedical materials.