It　is　more　and　more　urgent　to　develop　low　cost　magnetic　biochar　for　the　removal　of　pollutants　in　water.　In　this　study,　magnetic　biochar　composites　were　prepared　by　one-step　hydrothermal　synthesis　from　sewage　sludge　and　waterworks　sludge　(backwashing　iron　mud)　and　used　to　remove　methylene　blue　(MB)　from　water.　The　synthesized　samples　were　characterized　by　SEM,　EDS,　TEM,　XRD,　FTIR,　XPS,　VSM　and　BET.　By　changing　the　ratio　of　sludge　and　iron　mud,　three　kinds　of　sludge-based　magnetic　biochar　(SBMB)　with　good　properties　were　successfully　prepared.　When　the　proportion　of　iron　mud　was　higher,　the　samples　were　more　magnetic,　but　when　the　proportion　of　sludge　was　higher,　the　adsorption　capacity　of　the　samples　was　greater.　The　magnetic　materials　in　SBMB1,　SBMB2　and　SBMB3　were　Fe3O4,　and　their　saturated　magnetization　were　22.35　emu　g(-1),　45.16　emu　g(-1)　and　53.56　emu　g(-1),　respectively.　SBMB　had　a　good　capacity　for　methylene　blue　removal　and　the　process　was　rapid.　In　addition,　SBMB　had　good　magnetic　properties,　which　can　be　easily　separated　from　the　solution　by　magnet　after　the　experiment.　The　maximum　adsorption　capacities　of　SBMB1,　SBMB2　and　SBMB3　were　186.003　mg　g(-1),　178.786　mg　g(-1)　and　164.316　mg　g(-1),　respectively.　In　conclusion,　this　paper　reports　a　simple　and　environmentally　friendly　method　for　the　synthesis　of　magnetic　biochar　using　sludge　and　iron　mud　as　resources,　which　can　provide　a　reasonable　reference　for　the　treatment　of　sewage　sludge　and　backwashing　iron　mud　in　waterworks.