A　combined　system　consisting　of　a　up-flow　anaerobic　sludge　blanket　(UASB),　an　anoxic/aerobic　(A/O)　reactor　and　a　sequencing　batch　reactor　(SBR),　was　introduced　to　treat　a　mature　landfill　leachate　with　a　high　ammonia　concentration　and　low　ratio　of　COD/TN.　After　110　days　of　stable　operation,　the　results　indicated　that　denitrification　and　methanogenesis　took　place　simultaneously　in　the　UASB　and　then　the　denitrification　of　nitrite　and　nitrate　in　the　returned　sludge　by　using　the　residual　COD　was　accomplished　in　the　A/O　reactor.The　residual　ammonia　was　removed　in　SBR　as　well　as　nitrite　and　nitrate　produced　by　nitrification.　when　the　total　nitrogen　(TN)　concentration　of　influent　leachate　was　about　2080　mg/L　and　the　ammonia　nitrogen　concentration　was　about　1970　mg/L,　Nitrification　and　nitrogen　removal　were　usually　both　higher　than　99%　and　the　TN　and　ammonia　nitrogen　concentrations　of　final　effulent　were　about　12　mg/L　and　6　mg/L,　respectively.　The　shortcut　biological　nitrogen　removal　was　achieved　stably　both　in　A/O　reactor　with　FA　control　and　in　SBR　with　real-time　control　strategy　with　94%　and　93%　nitrite　accumulation,respectively,and　microbial　analysis　data　strongly　supported　that　AOB　and　NOB　competition　could　be　manipulated　through　long-term　application　of　both　real-time　control　strategy　and　FA　control　strategy.　©　2011　IEEE.