\Anammox　coupling　with　denitrification　has　attracted　increasing　attention　in　low-strength　wastewater　treatment.　However,　its　wide　application　in　continuous-flow　process　is　seriously　restricted　by　insufficient　anammox　capacity　due　to　the　failed　biomass　retention.　The　functional　capacities　of　communities　inhabiting　the　fluctuating　habitat　has　been　little　understood.　This　study　developed　a　novel　granular　sludge-based　partial　denitrification　coupling　with　anammox　(PD/A)　process　with　the　feeding　strategy　shifting　from　sequencing　to　continuous　flow　in　a　Continuous　Stirred　Tank　Reactor　(CSTR),　treating　low-strength　wastewater　containing　ammonia　(NH4+-N)　of　46.1　mg/L　and　nitrate　(NO3--N)　of　60.7　mg/L.　Significantly　enhanced　specific　anammox　activity　was　demonstrated,　attributed　to　the　robust　nitrite　(NO2--N)　generation　with　NO3--N　to　NO2--N　transformation　ratio　(NTR)　averaged　84.1　%.　Remarkable　total　nitrogen　(TN)　removal　of　95.4　%　was　thus　achieved　with　anammox　pathway　contribution　as　high　as　88.3　%.　Interestingly,　a　dynamic　and　stratified　microbial　structure　was　obtained　in　CSTR,　in　which　anammox　migrated　to　outer　layer　together　with　Thauera　capable　of　partial　denitrification　(PD)　in　big　granules,　resulting　in　more　efficient　cross-feeding　and　strengthening　the　cooperation　between　anammox　and　heterotrophic　PD　bacteria　in　CSTR.　Metagenomic-based　metabolic　inferences　provide　first　insight　into　the　versatile　microbial　metabolic　potential　of　anammox　bacteria　for　reducing　NO3--N　with　acetate　as　electron　donor　in　PD/A　process.　They　were　successfully　enriched　and　retained　with　the　relative　abundance　of　8.4　%,　being　attributed　to　the　enhanced　mass　transfer　efficiency.　On　the　contrary,　dominant　denitrifier　Thauera　decreased　sharply　to　4.2　%.　This　study　provides　a　new　alternative　of　anammox　coupling　with　heterotrophics　granular　sludge　for　efficient　low-strength　wastewater　treatment　under　continuous　feeding,　and　open　up　new　perspectives　for　selecting　distinctive　communities　that　stand　out　by　expansive　metabolic　versatility　and　excellent　microbial　collaboration.