With　the　inoculation　sludge　derived　from　a　sludge　fermentation　coupling　with　denitrification　system,　bath　experiments　were　conducted　to　investigate　the　effect　of　the　ratio　of　chemical　oxygen　demand　to　mass　concentration　of　NO3--N　and　pH　on　nitrite　accumulation　by　denitrification　using　wasted　sludge　fermentation　liquid　as　electron　donor.　The　results　show　that,　at　the　initial　nitrate　concentration　of　30　mg/L,　both　the　amount　and　rate　of　nitrite　accumulation　significantly　increase　when　the　initial　ρ(COD)/ρ(NOx--N)　changes　from　1　to　3,　and　is　less　influenced　by　a　further　increasement　of　ρ(COD)/ρ(NOx--N),　and　the　maximum　amount　of　nitrite　accumulation　is　(18.85±1.13)　mg/L　in　the　denitrification.　pH　has　a　significant　effect　on　nitrite　accumulation.　The　system　of　pH=7　shows　the　highest　nitrite　accumulation　rate.　However,　the　maximum　nitrite　accumulation　amount　is　in　the　system　of　pH=9,　followed　by　pH=6,　8　and　7.　In　addition,　the　nitrite　accumulation　ratio　(wNAR)　maintains　78%-95%　during　the　denitrifying　process　and　is　hardly　affected　by　the　initial　ρ(COD)/ρ(NOx--N),　which　may　be　due　to　the　culture　of　chronically　insufficient　carbon　source　for　denitrification　and　fermentation　conditions　introduce　in　the　sludge　fermentation　coupling　with　denitrification　system,　which　results　in　a　greater　ability　of　synthetizing　the　nitrate　reductase　than　the　nitrite　reductase　of　denitrifiers.　©,　2015,　Central　South　University　of　Technology.　All　right　reserved.