In　order　to　explore　an　effective　strategy　for　the　re-establishment　of　the　granular-flocculation　sludge　completely　autotrophic　nitrogenremoval　over　nitrite　(CANON)　process　after　the　side　flow　free　nitric　acid　(FNA)　treatment,　the　sequence　batch　reactors　(SBR)　reactor　was　used　to　conduct　experiments　to　explore　the　influence　of　different　recovery　methods　on　the　long-term　operation　performance　of　the　system,　so　as　to　realize　the　long-term　stable　operation　of　the　CANON　process.　Different　recovery　methods　had　a　great　impact　on　the　reconstruction　of　the　CANON　system.　The　R1using　the　ex-situ　high　aeration　recovery　strategy　re-established　a　stable　CANON　process　after　19days　of　operation,　while　the　in-situ　low　aeration　recovery　strategy　was　used.　Neither　R2nor　R3with　an　in-situ　high　aeration　recovery　strategy　was　able　to　effectively　re-establish　a　stable　CANON　process.　When　R1ran　stably　for　34days,　nitrite　oxidizing　bacteria　(NOB)　proliferation　appeared　again.　Regular　hydraulic　sieving　to　discharge　flocculent　sludge　for　FNA　treatment　to　achieve　the　＂double　suppression＂　of　dissolved　oxygen　(DO)　control　+　side　flow　FNA　treatment,　which　can　effectively　suppress　NOB　and　achieve　long-term　stable　operation　of　CANON　process.　Typical　cycle　analysis　results　showed　that　during　the　recovery　process,　the　activities　of　ammonia　oxidizing　bacteria　(AOB)　and　anaerobic　ammonia　oxidizing　bacteria　(AnAOB)　in　R1　were　higher　than　those　in　R2　and　R3,　and　the　activity　of　residual　NOB　in　the　reactor　was　effectively　inhibited.　With　the　re-establishment　of　the　CANON　process　in　R1,　the　proportion　of　simultaneous　nitrosation　and　anaerobic　ammonia　oxidation　(SNA)　denitrification　pathway　increased　from　8.91%　on　the　15th　day　to　19.39%　on　the　45th　day,　which　improved　the　removal　rate　of　NH4+-N.　©　2022　Chinese　Society　for　Environmental　Sciences.　All　rights　reserved.