Vacuum　ultraviolet/persulfate　(VUV/PS)　has　been　a　prospective　method　for　antibiotics　removal,　however,　the　enhanced　degradation　mechanism　is　still　unclear.　This　study　compared　the　sulfamethazine　(SMT)　degradation　by　VUV/PS　and　ultraviolet/persulfate　(UV/PS)　processes　using　a　photoreaction　system.　Results　showed　that　the　SMT　degradation　rate　and　PS　activation　rate　by　VUV/PS　was　1.36　times　and　1.39　times　those　of　the　conventional　UV/PS　process　under　the　same　dosage　of　PS,　respectively.　VUV/PS　also　achieved　a　high　SMT　mineralization.　SO4　center　dot(-)　and　HO　center　dot　played　important　roles　in　the　degradation　of　SMT　by　both　processes,　while　the　role　of　center　dot　O-2(-)　was　little.　SMT　concentration　changed　the　distributions　of　185　nm　and　254　nm　photons　absorbed　by　solution　components　and　altered　the　initiated　photolysis　reaction.　Both　processes　had　faster　degradation　rates　at　low　initial　SMT　concentrations　and　the　optimum　reaction　condition　was　at　solution　pH　of　5.　The　inhibited　level　of　the　SMT　degradation　in　both　processes　by　four　anions　was　in　the　following　order:　NO3-　＞　Cl-　＞　HCO3-　＞　SO42-.　VUV/PS　process　was　also　more　efficient　than　UV/PS　for　degrading　environmental　(200　mu　g/L)　and　high　(5　mg/L)　concentration　of　SMT　from　three　kinds　of　typical　water　matrices　(tap,　river　and　lake　water).　Finally,　ten　photo-products　of　SMT　degradation　by　VUV　(or　UV)　were　identified,　which　were　mainly　the　oxidized　products　of　C-N,　-NH2　and　S-C　on　SMT　molecules,　and　four　degradation　pathways　were　proposed.　Overall,　these　findings　could　provide　useful　insights　into　the　application　of　VUV/PS　in　efficient　antibiotics　removal　from　water.