With　the　development　of　psychiatric　disorder　in　the　current　society,　abuse　of　antidepressant　drug　fluoxetine　(FLX)　has　made　such　compound　an　emerging　contaminant　in　natural　waters,　and　causes　endocrine　systems　disturbance　on　some　aquatic　species.　Herein,　an　efficient　advanced　oxidation　process　(AOP),　electron　beam　irradiation　was　carried　out　to　investigate　the　decomposition　characteristics　of　such　novel　environmental　pollutant,　including　the　effects　of　initial　concentration,　pH,　radical　scavengers　and　anions.　The　results　showed　that　FLX　degradation　followed　pseudo-first-order　kinetics.　The　degradation　rate　and　dose　constant　decreased　with　increasing　initial　FLX　concentration;　and　G-values　elevated　with　the　increase　of　initial　concentration　but　reduced　with　increase　of　absorbed　dose.　Acidic　condition　was　more　conducive　to　FLX　destruction　than　neutral　and　alkaline.　The　radical　scavenger　experiments　indicated　center　dot　OH　was　the　main　reactive　species　for　the　decomposition　of　FLX,　while　the　reductive　species　e(aq)(-)　and　center　dot　H　played　an　adjuvant　role.　The　presence　of　anions　slightly　decreased　or　even　no　impact　on　FLX　degradation　rate.　Various　water　matrices　influenced　degradation　processes　of　FLX.　Experimental　results　suggested　radiolytic　degradation　showed　the　best　performance　in　pure　water　rather　than　natural　water　no　matter　with　filtration　or　not.　Moreover,　with　the　occurrence　of　defluorination　and　dealkylation　during　degradation　process,　some　organic　and　inorganic　intermediates　were　detected,　and　the　possible　degradation　mechanisms　and　pathways　of　FLX　were　proposed.　(C)　2017　Elsevier　Ltd.　All　rights　reserved.