An　anaerobic　ammonia　oxidation　(anammox)　and　denitrifying　immobilized　filler　coupling　reactor　(RAD)　was　established　to　systematically　evaluate　its　performance　for　enhancing　nitrogen　removal　using　endogenous　soluble　microbial　products　(SMPs)　in　the　absence　of　exogenous　COD,　and　was　compared　with　the　coupling　mode　with　exogenous　COD　addition.　The　results　showed　that　compared　with　independent　anammox　reactor　(RA),　the　RAD　can　effectively　use　SMPs　to　reduce　the　NO3−–N　yield　and　improve　the　total　nitrogen　removal　efficiency.　The　NO3−–N　yield　of　the　RAD　decreased　over　time　during　the　cycle,　decreasing　by　up　to　70　%　compared　to　the　RA.　3D-excitation　emission　matrix　showed　that　from　the　beginning　to　the　end　of　the　cycle,　the　SMP　components　changed　from　available　tryptophan　to　difficult-to-use　humic　acids.　In　addition,　the　temperature　and　reaction　cycle　affected　NOx−–N　transformation,　while　low　temperature　and　a　long　cycle　were　not　conducive　to　the　complete　reduction　of　NO3−–N,　leading　to　the　accumulation　of　NO2−–N.　In　contrast,　adding　exogenous　COD　accelerated　NO3−–N　removal　by　the　enhancing　denitrification　activity,　but　posed　a　potential　threat　to　anammox　activity.　High-throughput　sequencing　analysis　showed　that　Candidatus　Kuenenia　and　Halomonas　were　the　dominant　species　of　the　anammox　and　denitrifying　immobilized　fillers,　respectively,　which　supported　good　coupling　effect.　These　results　provide　valuable　information　for　the　optimization　of　anammox　systems　and　the　reduction　of　organic　carbon　consumption.　©　2022　Elsevier　Ltd