An　up-flow　sludge　blanket　(UASB)　and　sequencing　batch　reactor　(SBR)　system　was　introduced　to　remove　organics　and　nitrogen　from　landfill　leachate.　The　synergetic　effect　of　free　ammonia　(FA)　inhibition　and　process　control　was　used　to　achieve　the　nitrite　pathway　in　the　SBR.　In　previous　research,　inhibition　of　FA　on　nitrite　oxidizing　bacteria　(NOB)　activity　has　been　revealed　and　the　process　control　parameters　(DO,　ORP　and　pH)　exactly　indicate　the　end-point　of　nitritation.　The　method　was　implemented　in　the　SBR　achieving　stable　nitrogen　removal　via　the　nitrite　pathway　from　landfill　leachate.　The　degree　of　nitrite　accumulation　during　the　nitritation　was　monitored　along　with　the　simultaneous　and　advanced　removal　of　organics　and　nitrogen　in　the　UASB-SBR　system.　The　nitrifying　bacteria　community　was　quantitatively　analyzed　by　fluorescence　in　situ　hybridization　(FISH)　techniques.　Batch　tests　were　carried　out　to　investigate　the　denitritation　kinetics　of　microbial　bacteria　in　the　SBR.　Experimental　results　showed　that　the　nitrite　pathway　could　be　repeatedly　and　reliably　achieved　by　synergetic　effect　of　FA　inhibition　and　process　control.　FISH　analysis　showed　the　dominant　nitrifying　bacteria　were　ammonia-oxidizing　beta-Proteobacteria.　Relationship　between　nitrite　concentration　and　nitrite　reduction　rate　followed　the　Monod-type　equation.　The　maximum　specific　nitrite　utilization　rate　(k)　and　half-velocity　constant　(K-s)　were　calculated　as　0.44　gN　gVSS(-1)d(-1)　and　15.8　mg　L-1,　respectively.