A new anti-thrombosis dialytic membrane with a hydrophilic-hydrophobic microphase structure was prepared by pre-irradiation grafting of -hydroxyethyl methacrylate (HEMA) and styrene (St) onto polyethylene (PE) membranes. The effects of reaction conditions on the degree of grafting were determined, and the properties of the grafted films were investigated. Compared with PE grafted with hydrophilic monomer, the antithrombogenicity and permeability of the PE-g-(HEMA-co-St) were 30 and 15 times higher than that of the ungrafted films, respectively, if the volume ratio (HEMA:St) is about 1:1.