This　study　investigated　the　effects　of　substrate　shock　on　the　release　of　N-acyl-homoserine　lactones　(AHLs)　in　ANAMMOX　granules　and　the　relationship　between　AHL　release,　extracellular　polymeric　substance　(EPS)　excretion　and　the　properties　of　granules.　In　this　study,　a　transient　high　total　nitrogen　(TN)　concentration　of　2100　mg　L-1　for　24　h　stimulated　a　rapid　increase　in　N-hexanoyl-DL-homoserine　lactone　(C6-HSL)　and　N-octanoyl-DL-homoserine　lactone　(C8-HSL)　in　ANAMMOX　granules　resulting　in　abundant　EPS　excretion　and　deterioration　of　granule　settleability.　Substrate　shock　didn＇t　affect　the　distribution　of　AHLs　in　the　system.　C8-HSL　was　dominant　in　the　biomass　phase　without　EPS　and　C6-HSL　was　dominant　in　the　EPS　phase　and　the　biomass　phase　without　EPS.　The　results　of　the　batch　tests　also　confirmed　that　the　high　substrate　concentration　can　stimulate　the　release　of　abundant　C8-HSL　and　C6-HSL.　Loosely-bound　EPS　(LB-EPS)　excretion　was　closely　related　to　the　content　of　C8-HSL.　A　significant　increase　in　C8-HSL　from　222.6　to　1124.7　ng　L-1　occurred　when　the　substrate　concentration　increased　from　200　to　1200　mg　L-1,　leading　to　excessive　accumulation　of　LB-EPS,　which　was　considered　the　key　factor　for　the　deterioration　of　granule　stability　after　substrate　shock.　C6-HSL　could　stimulate　the　granule　activity.　Substrate　shock　triggered　the　release　of　abundant　C8-HSL,　leading　to　excessive　accumulation　of　EPS,　in　which　C6-HSL　was　dominant.　So　C6-HSL　increased　significantly　after　substrate　shock,　serving　to　maintain　bacteria　activity.　From　the　perspective　of　AHL-based　quorum　sensing,　this　study　confirmed　that　excessive　EPS　are　usually　excreted　under　extreme　environmental　stress　to　protect　bacteria　activity　while　this　self-defense　behavior　also　results　in　unstable　reactor　operation　performance.