Pristine　montmorillonite　(Mont)　samples　were　used　as　raw　materials　to　prepare　hydroxyl-Fe-pillared　Mont　(xOH/Fe-Mont,　x:　molar　ratio　of　OH/Fe),　hydroxyl-Al-pillared　Mont　(OH/Al-Mont)　and　hydroxyl-Fe-Al-pillared　Mont　(yFe/Al-Mont,　y:　molar　ratio　of　Fe/Al)　composites　for　the　adsorption　of　gentamicin　(Gen).　These　composites　were　comprehensively　characterized　through　X-ray　diffraction　(XRD)　and　Fourier　transformed　infrared　(FT-IR)　spectroscopy　to　reveal　the　adsorption　behavior　of　pristine　and　modified　Mont　for　Gen.　The　adsorption　capacity　of　the　Mont　composites　was　significantly　enhanced　after　modification,　with　the　adsorption　order　of　pristine　Mont　(42.83　mg/g)　≪　OH/Al-Mont　(63.50　mg/g)　＜　1.5OH/Fe-Mont　(70.50　mg/g)　≪　0.025Fe/Al-Mont　(87.20　mg/g).　Specifically,　the　Mont　composites　showed　the　maximum　adsorption　capacity　at　pH　9.　Furthermore,　Freundlich　adsorption　isotherm　model　could　well　fit　the　experimental　data.　The　pseudo-second-order　kinetic　model　could　sufficiently　describe　the　kinetics　of　Gen　adsorption,　showing　that　over　80%　of　the　equilibrium　adsorption　capacity　of　Gen　can　be　obtained　in　3h.　XRD　analysis　demonstrates　that　the　interlayer　expansion　in　hydroxyl-Fe　and　hydroxyl-Al　dominant　(y≤0.5)　pillared　montmorillonite　was　the　dominant　reason　for　the　enhancement　of　adsorption　capacity　of　Gen.　However,　this　is　not　a　crucial　indication　for　the　enhancent　in　adsorption　capacity　of　hydroxyl-Fe-Al-pillared　Mont　(y≥1.0).　Through　the　FT-IR　analysis,　cationic　exchange　was　the　dominant　mechanism　for　entering　of　both　Gen　and　and　hydroxyl-Al　into　the　interlayer　of　hydroxyl-Al　Mont.　©　2016,　Chinese　Society　for　Environmental　Sciences.　All　right　reserved.