In　order　to　improve　the　adsorption　capacity　of　chitosan　and　study　the　adsorption　of　diclofenac　from　aqueous　solution　by　chitosan,　magnetic　chitosan　beads　were　prepared　by　in-situ　coprecipitation　method　and　modified　by　ethylenediamine.　The　adsorption　capacity　of　the　modified　magnetic　chitosan　(EMMCS-G)　for　removal　of　diclofenac　in　water　was　investigated　with　different　dosages　of　cross-linking　agents　such　as　glutaraldehyde,　epichlorohydrin,　and　ethylenediamine,　and　results　show　that　the　optimal　adsorbent　was　EMMCS-G　when　the　dosages　of　glutaraldehyde,　epichlorohydrin,　and　ethylenediamine　were　4,　12　and　6　mL,　respectively.　EMMCS-G　was　characterized　by　scanning　electron　microscopy　(SEM),　transmission　electron　microscopy　(TEM),　vibrating　sample　magnetometer　(VSM),　Fourier　transform　infrared　(FTIR),　and　X-ray　diffraction　(XRD).　Effects　of　time,　temperature,　pH,　adsorbent　dosage,　and　regeneration　cycles　on　the　adsorption　of　diclofenac　by　EMMCS-G　were　investigated.　Results　show　that　Fe3O4　particles　were　successfully　coated　by　chitosan.　The　number　of　amino　groups　of　the　adsorbent　increased　significantly　after　modification,　and　the　modified　adsorbent　had　strong　magnetic　capacity　and　reusability.　The　optimum　pH　was　6.5.　When　the　initial　concentration　of　diclofenac　was　50　mg/L　and　the　dosage　of　the　adsorbent　was　100　mg,　the　removal　rate　was　above　76%　after　12　hours　of　reaction.　The　adsorption　process　accorded　with　the　pseudo　second-order　kinetic　model,　and　the　adsorption　data　fitted　well　with　the　Freundlich　model.　Based　on　the　thermodynamic　analysis　and　pH　experimental　results,　it　demonstrates　that　the　adsorption　process　was　endothermic　and　spontaneous,　which　was　mostly　controlled　by　physical　and　chemical　interactions.　Copyright　©2021　Journal　of　Harbin　Institute　of　Technology.All　rights　reserved.