Protein-imprinted　polyurethane-grafted　calcium　alginate　hydrogel　microspheres　were　prepared　and　characterized.　The　samples　were　investigated　with　optical　microscopy,　scanning　electron　microscopy,　13C-NMR,　and　Fourier　transform　infrared　spectroscopy.　We　proved　that　polyurethane　side　chains　were　successfully　grafted,　and　this　led　to　a　relatively　rough　and　dense　surface.　The　samples　exhibited　better　swelling　durability　when　applied　in　specific　adsorption　tests.　The　adsorption　kinetic　and　recognition　properties　indicated　that　the　imprinted　modified　microspheres　had　excellent　rebinding　affinity　toward　the　target　proteins.　Moreover,　the　influence　of　the　preassembly　pH,　rebinding　pH,　and　grafting　ratio　on　the　adsorption　capacity　and　imprinting　efficiency　(IE)　were　systematically　investigated.　The　study　results　suggest　that　the　modified　samples　possessed　a　higher　IE　toward　the　target　protein　under　the　optimum　pH　and　grafting　ratio.　Upon　polyurethane　grafting　modification,　the　alginate　hydrogel　microspheres　showed　improved　mechanical　stability　and　recognition　specificity.　©　2015　Wiley　Periodicals,　Inc.