Sludge　alternate　anaerobic/anoxic　fermentation　system(SAF)　was　established　by　adding　nitrate　to　the　waste　activated　sludge(WAS)　anaerobic　fermentation　system,　therefore　it　created　an　alternate　anaerobic/anoxic　process　for　the　sludge　simultaneous　fermentation　and　denitrification.　In　this　research,　the　overall　performance　was　analysisd　both　in　SAF　and　typical　anaerobic　fermentation(TAF),　in　order　to　study　the　characteristics　of　fermentation　and　denitrification.　Both　of　the　performance　in　two　systems　stabilised　till　the　60th　day,　SAF　achieved　higher　sludge　reduction,　while　owned　less　productivity　of　fermentation　product　compared　to　TAF.　SAF　showed　its　excellent　denitrifying　ability　in　the　overall　process,　which　proved　the　feasibility　of　simultaneous　fermentation　and　denitrification　in　it.　Besides,　the　trend　of　pH,　ORP　could　be　the　indicators　of　denitrification　in　SAF.