The present invention provides a method for improving blood compatibility of interpenetrating multicomponent polymer by controlling various factors affecting phase separation such as composition ratio, synthetic temperature, synthetic pressure, cross-linking density and hydrophilicity of polyurethane in the course of synthesizing interpenetrating polymer network ("IPN") where hydrophilic urethane resin and hydrophobic styrene derivative are cross-linked each other. IPN materials of the invention may be widely used in various applications such as artificial organ or surface finishing material which are in direct contact with blood, since they inhibit thrombogenesis by suppressing platelet adhesion and agglutination.