Polyvinylidene　fluoride　(PVDF)　flat　ultrafiltration　membranes　was　modified　with　multi-walled　carbon　nanotube　(MWCNTs)　to　remove　humic　acid　(HA).　To　understand　the　mechanism　of　MWCNTs　on　membrane　fouling　control　in　the　removal　of　HA,　the　adsorption　and　the　interception　performances　of　the　pre-deposited　MWCNTs　(MWCNTs　layer)　were　systematically　compared.　Besides,　the　effects　of　MWCNTs　dosage　and　solution　ions　were　further　analyzed.　The　results　reveal　that　MWCNTs　deposition　was　benefit　for　fouling　control.　The　MWCNTs　layer　formed　by　using　ethanol　as　dispersant　had　the　optimal　efficiency　on　fouling　alleviation.　Increasing　the　MWCNTs　dosage　can＇t　increase　the　adsorption　and　retention　of　HA　indefinitely.　The　addition　of　Na+　will　reduce,　but　Ca2+　can　improve　the　adsorption　and　retention　of　HA　by　MWCNTs.　The　fouling　membrane　surface　was　observed　with　optical　and　scanning　electron　microscope.　The　results　demonstrate　that　the　pre-deposited　MWCNTs　dispersed　with　ethanol　had　a　uniform　layer　structure.　HA　was　retained　in　the　porous　structure　of　the　MWCNTs　layer　and　was　difficult　to　enter　the　PVDF　membrane　pores.　HA　was　easily　desorbed　easy　desorption　of　HA　during　backwash　improves　the　membrane＇s　reversibility.　However,　MWCNTs　despersed　with　water　were　prone　to　aggregate.　HA　was　tend　to　adhere　on　the　PVDF　membrane　surface　or　enter　into　the　pores　of　PVDF　membrane,　which　reduced　membrane　reversibility.　After　pre-adsorption　of　HA　by　MWCNTs,　complex　pollution　of　MWCNTs/HA　would　form　on　the　surface　of　PVDF　membrane,　if　not　removed　by　microfiltration.　©　2019,　Science　Press.　All　right　reserved.