The　present　study　reports　the　inhibition　kinetics　and　granular　sludge　in　an　anaerobic　ammonium　oxidation　(ANAMMOX)　-　up-flow　anaerobic　sludge　blanket　reactor　fed　with　diluted　mature　landfill　leachate.　The　activity　of　ANAMMOX　bacteria　was　inhibited　by　addition　of　mature　landfill　leachate,　but　gradually　adapted　to　the　leachate.　The　system　achieved　efficient　nitrogen　removal　during　65-75　d　and　the　average　removal　efficiencies　for　NH4+-N,　NO2--N　and　total　nitrogen　(TN)　were　96%,　95%　and　87%,　respectively.　ANAMMOX　was　the　main　pathway　of　nitrogen　removal　in　the　system,　and　heterotrophic　denitrification　occurred　simultaneously.　In　addition,　aerobic　ammonia　oxidation　and　aerobic　nitrite　oxidation　were　active　in　this　system.　Inhibition　kinetic　experiments　showed　that　the　NH4+-N　and　NO2--N　inhibition　concentration　threshold　of　ANAMMOX　were　489.03　mg/L　and　192.36　mg/L,　respectively.　ANAMMOX　was　significantly　inhibited　by　mature　landfill　leachate,　and　was　completely　inhibited　when　the　leachate　concentration　was　1,450.69　mg/L　(calculated　in　chemical　oxygen　demand).　Thus,　the　inhibition　concentration　of　substrate　and　landfill　leachate　should　be　considered　when　applying　the　ANAMMOX　process　to　landfill　leachate.　The　color　of　granular　sludge　ANAMMOX　changed　from　brick-red　into　a　reddish-brown.　The　particle　size　increased　from　small　to　large,　with　evident　granulation　of　the　ANAMMOX　sludge.