Magnetic　carboxyl-functionalized　crosslinked　copolymer　microspheres　of　α-methyl　styrene　and　maleic　anhydride　(MCPMs)　with　a　uniform　particle　size　were　synthesized　based　on　self-stabilized　precipitation　polymerization.　Magnetic　crosslinked　copolymer　microspheres　(MPMs)　were　prepared　by　in　situ　polymerization　using　oleic　acid-modified　Fe3O4　as　the　magnetic　source,　α-methyl　styrene　and　maleic　anhydride　as　monomers　and　divinylbenzene　as　the　crosslinking　agent,　and　MCPMs　were　then　obtained　by　hydrolyzing　the　anhydride　groups　of　MPMs　into　carboxyl　groups.　The　as-prepared　MCPMs　were　characterized　by　scanning　electron　microscopy,　Fourier-transform　infrared　spectroscopy,　vibrating　sample　magnetometry　and　the　Brunauer–Emmett–Teller　method.　The　adsorption　behavior,　adsorption　kinetics　and　adsorption　isotherms　of　MCPMs　for　methylene　blue　(MB)　removal　from　water　were　systematically　investigated.　It　was　found　that　MCPMs　manifested　good　MB　removal　ability　from　water　with　a　maximum　MB　adsorption　capacity　of　315 mg/g.　The　kinetic　and　isothermal　data　of　MCPMs　for　MB　removal　followed　the　pseudo-second-order　model　and　the　Langmuir　isothermal　model,　respectively.　In　addition,　MB-loaded　MCPMs　could　be　separated　easily　by　magnets,　and　the　MB　removal　rate　of　MCPMs　still　reached　more　than　90.0%　after　five　cycles.　These　results　indicate　that　MCPMs　have　great　potential　in　cationic　dye　wastewater　treatments.