A　novel　core-shell　magnetic　composites　[Fe3O4@C@FeOx　(FCF)]　(Fe3O4　as　the　core　and　C　as　the　inner　shell,　FeOx　as　the　outer　shell)　was　prepared　by　modifying　Fe3O4@C　magnetic　nanoparticles　(FC)　by　amorphous　iron　oxides　to　remove　As(V)　from　water.　Both　the　magnetic　core　(FC)　and　the　amorphous　iron　oxide　shell　were　all　fabricated　with　Iron-containing　water　treatment　residuals　(WTRs),　also　called　iron　sludge.　X-ray　diffraction　(XRD),　Fourier　transform　infrared　spectroscopy　(FTIR),　transmission　electron　microscopy　(TEM),　Brunauer-Emmett-Teller　analysis　(BET),　X-ray　photoelectron　spectroscopy　(XPS)　and　vibrating　sample　magnetometer　(VSM)　were　utilized　to　characterize　the　FC　and　FCF.　TEM　images　clearly　show　that　FCF　is　composed　of　spherical　particles　with　obvious　core-shell　structure,　and　the　thickness　of　carbon　shell　and　amorphous　iron　oxide　shell　are　20-35　and　30-50　nm,　respectively.　With　saturation　magnetization　of　16.30　emu/g,　FCF　nanoparticles　could　be　easily　separated　from　the　solution　with　a　hand　held　magnet.　BET　analysis　show　that　the　specific　surface　area　of　FCF　is　122.7　m(2)/g,　which　is　conducive　to　the　adsorption　of　As(V).　The　adsorption　efficiency　of　FCF　for　As(V)　is　high　in　a　wide　range　of　pH　3-9.　Moreover,　the　adsorption　process　might　be　a　chemical　adsorption　according　to　kinetics　fitting　analysis　of　FCF.　Both　Langmuir　and　Freundlich　model　could　fit　the　adsorption　data　for　the　FCF　at　25　degrees　C　and　35　degrees　C　well,　and　the　maximum　adsorption　capacity　of　FCF　(13.47　mg/g)　at　25　degrees　C　is　about　3.29　times　of　that　of　FC　(3.14　mg/g),　which　may　be　due　to　the　large　amount　of　amorphous　iron　oxides　coated　on　the　surface　of　FCF　and　its　large　specific　surface　area.　This　study　not　only　provides　a　new　way　for　the　disposal　of　waste　iron　sludge,　but　also　supplies　a　cheap　and　stable　adsorbent　for　the　treatment　of　arsenic-containing　water.