This　study　evaluated　gamma　radiation-enhanced　sulfamethazine　(SMT)　degradation,　which　belongs　to　the　heterocyclic　sulfonamides,　in　different　conditions　in　aqueous　solution.　The　results　showed　that　gamma　irradiation　could　increase　the　SMT　removal　in　aqueous　solution,　and　the　SMT　degradation　kinetic　follow　the　modified　pseudo-first-order　kinetic.　The　degradation　rate　was　nearly　95%　at　the　absorbed　dose　of　4　kGy.　The　removal　of　total　organic　carbon　(TOC)　and　total　nitrogen　(TN)　could　be　also　induced.　When　the　radiation　dose　was　5　kGy,　the　removal　rates　were　only　about　6.8%　and　10.5%　for　TOC　and　TN,　respectively.　Some　ions　including　HCOO-,　CH3COO-　and　SO42-　released　during　SMT　degradation　were　studied.　The　biodegradability　and　toxicity　of　intermediate　products　of　the　SMT　degradation　were　also　proposed　in　this　experiment.　The　biodegradability　of　the　SMT　can　be　improved　by　the　intermediate　products　of　SMT　degradation　at　the　radiation　dose　of　1,　2　and　5　kGy.　Gamma　radiation　could　be　used　as　a　pretreatment　technology　before　the　biodegradation　process　of　pharmaceutical　waste　water.