Abuse　of　antibiotics　and　consequent　formation　of　resistance　genes　has　aroused　public　concerns　on　environmental　issues.　Herein,　we　employed　electron　beam　(EB)　approach　to　deal　with　three　kinds　of　sulfonamides,　for　studying　the　treatment　efficiency　and　removal　mechanisms　to　these　widely　used　drugs.　The　results　suggested　EB　could　efficiently　decompose　the　parent　compounds　of　sulfonamides,　the　degradation　processes　followed　pseudo-first　order　kinetics,　and　dose　constant　k　decay　exponentially　with　their　initial　concentration.　The　radiolysis　efficiency　of　these　sulfonamides　with　the　sequence　of　sulfathiazole　(STZ)　＞　sulfamethoxazole　(SMX)　＞　sulfamethazine　(SMZ).　The　highested　decomposition　efficiencies　were　achieved　in　purewater　compared　to　tipwater　and　surfacewater　solutions.　Acidic　solutions　facilitated　sulfonamides　radiolytic　decomposition.　An　appropriate　amount　of　5　mM　H2O2　enhanced　sulfonamides　degradation.　Removal　efficiencies　were　also　influenced　by　inorganic　anions　in　the　order　of　NO2-　＞　SO32-　＞　CO32-　＞　NO3-　＞　HCO3-　＞　Cl　＞　SO42-.　Hydroxyl　radicals　were　the　dominant　species,　which　was　proven　by　radical　scavenging　studies.　Removal　of　total　organic　carbon　and　total　nitrogen　were　also　determined　to　evaluate　the　mineralization　degrees　of　sulfonamides.　The　formation　of　three　ionic　products　and　the　identification　of　more　than　10　organic　intermediates　were　performed.　Combining　with　the　radical　effects　and　intermediates,　possible　degradation　mechanisms　of　sulfonamides　by　EB　radiolysis　were　proposed.　Moreover,　tests　of　luminous　bacteria　demonstrated　EB　could　decrease　the　acute　toxicity　to　the　aquatic　ecosystems.