A new-type sulphonated polymer surface obtained by the solution technique is reported. The surface properties of the mortified polymer surfaces are characterized by SEM and ESCA, and their in vitro blood compatibility is evaluated in terms of TT, PRT, PTT, and platelet adhesion. The modified polymer surface is found to be the least thrombogenic when the modifying polymer molecule contains hydrophilic PEO chains. The PEO chains can serve as "spacers" inserted into the film surface and SO3-group. This kind of polymer surface is easily mobile for reconstructing to carry out the function of the SO3- group and PEO chains.