Endogenous　substances,　such　as　organic　acids　in　food,　can　interfere　with　the　detection　of　trace　residues.　To　eliminate　this　effect,　the　magnetic　adsorbent　material　was　obtained　by　directly　modifying　acidified　Fe3O4　with　Nβ-(aminoethyl)-γ-aminopropyltrimethoxysilane　(KH792)　as　an　amination　reagent.　The　optimal　modification　condition　of　KH792　for　acidified　Fe3O4　was　optimized　by　response　surface　methodology,　which　was　82.5℃,　pH=4.9,　and　KH792　addition　of　1.8　mL.　Under　these　optimal　conditions,　the　acidified　Fe3O4　directly　modified　by　KH792　has　an　adsorption　capacity　of　22.8　mg/g　and　shows　a　188%　increase　in　the　adsorption　capacity　of　the　gallic　acid　compared　to　commercially　available　Fe3O4.　Additionally,　the　modified　Fe3O4　exhibits　excellent　performances　of　rapid　solid-liquid　separation,　good　stability,　and　dispersibility.　The　properties　of　the　directly　modified　products　were　characterized　by　BET,　Zeta　potential,　FTIR,　and　XPS.　The　results　show　that　KH792　bonds　on　Fe3O4　surface　hydroxyl　group＇s　by　Fe−　O−　Si　bonding,　and　acidification　improves　the　number　of　hydroxyl　groups　on　Fe3O4　surface,　thus　improving　the　KH792　modification　for　Fe3O4.　The　magnetic　products　prepared　in　this　work　can　be　used　for　the　purification　of　organic　acids　in　complex　sample　matrices.　©　2024　Beijing　University　of　Aeronautics　and　Astronautics　(BUAA).　All　rights　reserved.