Sulfate　in　wastewater　can　be　reduced　to　sulfide　and　its　impact　on　the　stability　of　enhanced　biological　phosphorus　removal　(EBPR)　is　still　unclear.　In　this　study,　the　metabolic　changes　and　subsequent　recovery　of　polyphosphate　accumulating　organisms　(PAOs)　and　glycogen　accumulating　organisms　(GAOs)　were　investigated　at　different　sulfide　concentrations.　The　results　showed　that　the　metabolic　activity　of　PAOs　and　GAOs　was　mainly　related　to　H2S　concentration.　Under　anaerobic　conditions,　the　catabolism　of　PAOs　and　GAOs　was　promoted　at　H2S　concentrations　below　79　mg/L　S　and　271　mg/L　S,　respectively,　and　inhibited　above　these　concentrations;　whereas　anabolism　was　consistently　inhibited　in　the　presence　of　H2S.　The　phosphorus　(P)　release　was　also　pH-dependent　due　to　the　intracellular　free　Mg2+　efflux　from　PAOs.　H2S　was　more　destructive　to　the　esterase　activity　and　membrane　permeability　of　PAOs　than　those　of　GAOs　and　prompted　intracellular　free　Mg2+　efflux　of　PAOs,　resulting　in　worse　aerobic　metabolism　and　subsequent　recovery　of　PAOs　than　GAOs.　Additionally,　sulfides　facilitated　the　production　of　extracellular　polymeric　substances　(EPS),　especially　tightly　bound　EPS.　The　amount　of　EPS　in　GAOs　was　significantly　higher　than　that　in　PAOs.　The　above　results　indicated　that　sulfide　had　a　stronger　inhibition　to　PAOs　than　GAOs,　and　when　sulfide　was　present,　GAOs　had　a　competitive　advantage　over　PAOs　in　EBPR.