The　resource　utilization　of　water　treatment　residuals　is　a　hot　topic　in　current　research.　In　this　work,　a　kind　of　carbon-doped　magnetic　nanoparticle　(Fe3O4@C)　was　prepared　using　backwashing　iron　mud　from　the　groundwater　treatment　plant　as　raw　material.　The　Fe3O4@C　was　used　for　the　magnetic　coagulation　(MC)　process　to　evaluate　the　superiority　of　the　MC　process　via　comparing　it　with　the　traditional　coagulation　(TC)　process.　Meanwhile,　the　Fe3O4　was　also　used　for　reference　in　the　MC　process　to　assess　the　potential　and　feasibility　of　the　Fe3O4@C.　The　synthesized　Fe3O4@C　was　characterized　by　SEM,　TEM,　XRD,　VSM,　and　XPS.　Then,　coagulation　performances　and　flocs　properties　were　evaluated　in　both　TC　and　MC　processes.　In　addition,　the　various　roles　of　magnetic　particles　in　the　MC　process　were　discussed.　The　results　showed　that　the　participation　of　Fe3O4@C　increased　the　turbidity　removal　rate　from　90.3%　to　96.8%,　the　ultra-violet　absorbance　at　254　nm　(UV254)　removal　rate　from　81.4%　to　86.5%,　the　dissolved　organic　carbon　(DOC)　removal　rate　from　60.4%　to　66.9%,　and　the　residual　Al　content　dropped　from　2.54　mg/L　to　2.07　mg/L.　Especially,　it　is　found　the　Fe3O4@C　had　the　potential　to　remove　more　small　molecular　weight　organic　matter　during　the　coagulation　process.　The　flocs　were　loose　and　easily　broken　due　to　the　formation　of　the　Al　species-nanoparticle　cluster.　Fe3O4@C　involved　MC　process　can　achieve　the　same　water　treatment　efficiency　as　Fe3O4　involved　MC　process,　or　even　better.　Especially,　the　magnetic　seed　of　Fe3O4@C　based　on　waste　utilization　can　not　only　reduce　the　cost,　but　also　has　a　good　adsorption　on　small　molecular　organics.　This　provides　a　new　reference　way　for　the　utilization　of　iron　mud　and　the　development　of　magnetic　seed　in　the　MC　process.