Exogenous　addition　of　acylhigh　serine　lactones　(AHLs)　can　improve　the　activity　of　anaerobic　ammonia　oxidation　bacteria　(AAOB),　which　is　conducive　to　the　rapid　start-up　of　anaerobic　ammonia　oxidation　(ANAMMOX).　However,　the　acquisition　of　AHLs　increases　the　operating　cost.　Based　on　this,　a　two-stage　ANAMMOX　series　reactor　was　constructed　in　this　study　to　make　full　use　of　the　effluent　active　components　of　the　primary　reactor　(R1)　to　realize　the　rapid　start-up　of　the　post-reactor　(R2).　In　the　experiment,　R1　effluent　was　used　as　the　influent,　and　gradually　transferred　to　the　R1　effluent　clear　liquid　and　synthetic　wastewater　as　the　influent.　The　feasibility　of　the　strategy　was　verified　by　nitrogen　removal　performance,　sludge　characteristics　and　microbial　community　changes,　and　the　relevant　mechanism　was　analyzed.　The　results　showed　that　R2　achieved　rapid　start-up　on　the　56th　day,　its　total　nitrogen　volume　load　was　0.6-0.7　kg·(m3·d)-1　after　operation　for　90　days,　and　its　total　nitrogen　removal　efficiency　could　reach　higher　than　93%,　which　was　significantly　higher　than　that　of　the　control　group　(R3,　61%)　started　with　synthetic　sewage　directly.　This　was　attributed　to　the　fact　that　the　sludge　lost　from　R1　provided　a　stable　biomass　supplement　for　R2,　and　the　quorum-sensing　signal　molecules　contained　in　its　supernatant　promoted　the　activity　of　AAOB　in　R2.　High-throughput　sequencing　results　showed　that　the　organic　matter　introduced　into　R1　effluent　led　to　an　increase　in　R2　community　diversity　and　the　proportion　of　heterotrophic　bacteria　such　as　denitrification,　and　a　decrease　in　the　proportion　of　ANAMMOX　functional　bacteria　Candidatus　Brocadia.　However,　compared　with　R1,　the　expression　levels　of　transport　and　metabolity-related　functional　genes　in　R2　were　up-regulated.　These　results　indicate　that　it　is　feasible　to　realize　the　rapid　start-up　of　the　post-reactor　through　two-stage　ANAMMOX　series.　©　2022,　Science　Press.　All　right　reserved.