The　effective　degradation　of　Sulfamethoxazole　(SMX)　is　of　great　importance　to　alleviate　environmental　pollution.　In　this　study,　the　degradation　capacity　of　an　ordinary　sequencing　batch　activated　sludge　system　(SBR)　and　montmorillonite　(MMT)　system　was　compared　for　their　ability　to　degrade　different　concentrations　of　SMX.　Compared　with　SBR　system,　the　MMT　system　exhibited　higher　stability　and　degradation　capacity.　The　changes　in　the　composition　of　tightly　bound　extracellular　polymeric　substances　(TB-EPS)　were　likely　key　to　the　observed　stability　of　the　system.　High　concentrations　of　SMX　inhibited　the　degradation　performance　of　SBR.　MMTsupplemented　reduced　the　generation　of　antibiotic　resistance　genes　(ARGs).　Thauera　is　a　gene　that　is　able　to　degrade　SMX,　and　its　abundance　in　MMT　system　reached　7.84%.　As　potential　hosts　of　ARGs,　the　proportions　of　Paenarthrobacter　and　Caldilineacea　were　significantly　correlated　with　sulfonamide　resistance　genes　(sul1　and　sul2).　Overall,　MMT-supplemented　system　was　found　to　be　a　favorable　method　of　treating　antibiotic.