As　a　low　consumption　and　high　efficiency　process,　Partial　Nitrification-Anammox/denitratation　(PNAD)　was　applied　to　co-treat　mature　landfill　leachate　with　municipal　sewage　for　300　days.　Specifically,　ammonia　(670.2 ± 63.7 mg N/L)　contained　in　mature　landfill　leachate　was　firstly　oxidized　to　nitrite　(611.5 ± 28.1 mg N/L)　in　sequence　batch　reactor　(SBRPN);　meanwhile,　organic　matter　in　municipal　sewage　was　partially　removed　in　another　reactor　(SBROMR);　finally,　nitrite　produced　(611.5 ± 28.1 mg N/L)　in　SBRPN　and　ammonia　(53.1 ± 6.4 mg N/L)　residing　in　pretreated　municipal　sewage　were　simultaneously　degraded　through　combined　Anammox-denitratation　process　in　an　up-flow　anaerobic　sludge　bed　(UASBAD).　A　satisfactory　effluent　quality　of　10.3 mg/L　TN　was　obtained　after　long-term　operation,　with　Anammox　and　denitrification　contributing　to　86.2%　and　5.8%　nitrogen　removal　efficiency,　respectively.　Mass　balance　confirmed　67.2%　nitrate　generated　from　Anammox　could　be　reduced　to　nitrite　and　in-situ　reused.　Anammox　bacteria　genes　and　nitrate　reductase/nitrite　reductase　ratio　were　highly　detected,　accelerating　combined　Anammox-denitratation.　Further,　Ca.　Brocadia　triumph　among　various　Anammox　bacteria　groups,　increasing　from　1.2%　(day　120)　to　3.6%　(day　280).