Monodisperse　cross-linked　superparamagnetic　poly(St-AA)/Fe3O4　microspheres　with　carboxyl　group　on　the　surface　were　prepared　via　miniemulsion　copolymerization.　The　morphology,　composition,　magnetic　properties,　and　crystalline　structure　of　the　magnetic　microspheres　were　characterized　by　transmission　electron　microscopy,　vibrating　sample　magnetometer,　X-ray　diffraction,　Fourier　transform　infrared　spectroscopy　and　thermogravimetric　analysis　methods,　respectively.　The　effect　of　crosslinker　during　polymerization　on　the　particle　morphology　was　studied.　The　relationship　between　the　adsorbed　weight　of　bovine　serum　albumin　(BSA)　on　microspheres　and　adsorption　time　and　pH　was　also　investigated.　Moreover,　poly(St-AA)/Fe3O4　microspheres　displayed　excellent　adsorption　capabilities　on　BSA　and　the　adsorbed　weight　of　BSA　was　improved　with　the　increasing　AA　content　in　the　poly(St-AA)/Fe3O4　microspheres.　(C)　2013　Elsevier　B.V.　All　rights　reserved.