Effects　of　substrate　shock　on　the　characteristics　of　ANAMMOX　granules　were　investigated　from　the　perspective　of　quorum　sensing　with　the　final　purpose　of　providing　theoretical　guidance　and　reference　for　improving　the　stability　and　settleability　of　ANAMMOX　granules　under　substrate　shock.　The　results　showed　that　due　to　24h　1500mg/L　total　nitrogen　(TN)　shock,　the　amount　of　AHLs　released　by　ANAMMOX　granules　increased　significantly　from　4.3　to　10.0.　At　the　same　time,　excessive　release　of　bound　extracellular　polymeric　substances　(B-EPS)　(increased　by　107.3mg/g　VSS)　was　observed,　which　led　to　the　poor　settling　performance　of　granules　(density　and　settling　velocity　reduced　by　53%　and　33%,　respectively).　However,　after　the　TN　concentration　returned　to　the　level　in　the　stable　period,　the　release　amount　of　AHLs,　B-EPS　content　and　granules　properties　could　also　return　gradually　to　the　level　in　the　stable　period.　It　was　inferred　that　substrate　shock　resulted　in　the　change　of　release　amount　of　AHLs,　which　caused　the　change　of　B-EPS　production.　The　results　of　the　batch　test　also　confirmed　that　the　substrate　concentration　affected　the　release　of　AHLs,　significantly.　Moreover,　B-EPS　production　was　closely　related　to　the　release　amount　of　AHLs.　When　the　TN　concentration　was　1000mg/L,　the　release　amount　of　AHLs　was　up　to　11.7,　leading　to　excessive　accumulation　of　loosely-bound　EPS　(LB-EPS)　(increased　by　69mg/g　VSS)　and　poor　settleability　of　granules　comparing　with　200mg/L　TN　concentration.　In　contrast,　the　tightly-bound　EPS　(TB-EPS)　content　was　not　affected　by　substrate　concentration.　Thus,　the　LB-EPS　was　considered　the　key　factor　for　the　deterioration　of　granule　settleability.　Low　concentration　inhibitor　can　effectively　inhibit　the　excessive　release　of　AHLs　caused　by　high　substrate　concentration,　resulting　in　36%　reduction　in　LB-EPS　content　and　improvement　of　the　settleability　and　activity　of　granules.　©　2019,　Editorial　Board　of　China　Environmental　Science.　All　right　reserved.