The　widespread　use　of　tetracycline　(TC)　is　a　non-negligible　cause　of　environmental　pollution,　such　as　antibiotic　resistance　genes　(ARGs).　Economical,　green　and　efficient　treatment　methods　are　urgently　needed.　In　this　study,　the　magnetic　N-doped　iron　sludge　based　biochar　(N-BCFe)　was　prepared　by　a　one-step　pyrolysis　method　using　the　iron-containing　sludge　from　groundwater　treatment　plants,　sycamore　leaves　and　urea　as　raw　materials　to　active　persulfate　(PS)　for　TC　degradation.　The　results　show　that　under　the　optimal　experimental　conditions,　the　removal　rate　of　10　mg/L　TC　in　the　N-BCFe/PS　system　could　reach　86.56%　(120　min),　accompanied　by　a　59.9%　reduction　in　total　organic　carbon　(TOC),　and　still　63.34%　of　TC　was　removed　in　the　third　recycle　experiment.　Combined　with　EPR,　free　radical　quenching　experiments　and　XPS　spectra,　it　is　confirmed　that　there　are　free　radicals　(SO4　center　dot-,(OH)-O-center　dot)　and　non-radical　(O-1(2))　pathways　in　N-BCFe/PS　system.　And　the　former　is　related　to　Fe　doping,　while　the　latter　is　attributed　to　N　doping　(nitrogen-containing　functional　groups).　Seventeen　TC　intermediates　were　identified　by　LC-MS　technology,　and　three　TC　degradation　pathways　were　established　accordingly.　Generally,　this　study　illustrates　the　considerable　catalytic　potential　of　N-BCFe　and　provides　valuable　insights　into　the　synthesis　of　catalysts　prepared　from　iron-containing　sludge　as　feedstock.