The　electro-Fenton　(EF)　technique　has　attracted　great　interest　in　the　treatment　of　landfill　leachate　concentrate　(LLC).　Active　carbon　fiber　(ACF)　was　modified　with　graphitic　carbon　nitride　(g-C3N4),　carbon　nanotubes　(CNTs)　and　polytetrafluoroethylene　(PTFE)　through　a　wet　ultrasonic　impregnation-calcination　process,　which　enhanced　the　production　of　H2O2　and　regeneration　of　active　Fe(ii)　in　an　EF　system.　The　experiments　on　physicochemical　characterization　demonstrated　that　the　modified　ACF　was　provided　with　more　active　sites　and　the　hydrophobicity　of　the　electrode　was　improved,　facilitating　the　O-2　mass　transfer.　Through　comparison　with　pristine　ACF,　g-C3N4/ACF　and　CNTs/ACF,　electrochemical　experiments　showed　that　g-C3N4/CNTs/ACF　exhibited　the　best　performance　on　the　electrocatalytic　activity　of　the　oxygen　reduction　reaction　(ORR)　and　electron　transfer　efficiency　attributed　to　the　synergetic　effect　of　g-C3N4　and　CNTs.　Fulvic　acids　(FA)　were　used　to　simulate　LLC　to　investigate　the　effect　of　operational　parameters　on　EF　performance.　Under　optimal　conditions,　H2O2　production　of　g-C3N4/CNTs/ACF　reached　132　mg　L-1　with　an　H2O2　generation　rate　of　3.96　mg　h(-1)　cm(-2)　and　86%　FA　was　removed　with　a　kinetic　rate　of　0.046　within　2　h.　Simultaneously,　the　concentration　of　dissolved　Fe2+　in　the　system　increased　from　2.5　mg　L-1　to　6.4　mg　L-1　after　modification,　thus　continuously　reacting　with　H2O2　to　produce　more　OH.　Remarkably,　an　excellent　EF　performance　was　achieved　with　g-C3N4/CNTs/ACF　in　the　treatment　of　LLC,　where　74.7%　of　TOC　was　removed　with　an　economical　energy　consumption　of　5.76　kW　h　kg(TOC)(-1)　and　biodegradability　was　improved　significantly,　as　concluded　from　the　results　of　UV-vis　and　a　3D　excitation-emission　matrix　(EEM).　After　10　cycles,　H2O2　production　could　still　reach　120　mg　L-1　and　the　mineralization　rate　remained　at　66%.　This　work　develops　an　efficient,　cost-effective,　and　durable　EF　cathode　for　the　treatment　of　LLC.