The　feasibility　of　enhancing　anammox　enrichment　in　sewage　treatment　through　fixed　biofilm　was　investigated　in　this　study.　Two　reactors　were　used　to　treat　real　domestic　sewage　and　operated　in　an　identical　mode:　one　is　a　sequencing　biofilm　batch　reactor　(SBBR)　with　blank　carriers　and　the　other　is　a　sequencing　batch　reactor　(SBR)　without　carriers.　After　anammox　sludge　inoculation　and　160　days＇　operation,　the　abundance　of　the　anammox　bacteria　increased　to　2.58　x　109　gene　copies/g　dry　sludge　in　the　biofilm　of　SBBR,　but　decreased　to　8.18　x　107　gene　copies/g　dry　sludge　in　the　activated　sludge　of　SBR.　The　nitrogen　removal　efficiency　(NRE)　of　SBBR　and　SBR　was　79.3%　and　57.9%,　respectively.　Further　analysis　suggests　that　the　partial　nitrification　was　stabilized　in　SBBR　due　to　the　addition　of　carriers　and　the　dominating　nitrogen　removal　pathway　was　the　anammox　reaction.　In　general,　the　fixed　biofilm　effectively　maintained　and　enriched　the　anammox　bacteria,　which　benefitted　the　startup　and　steady　operation　of　the　sewage　partial　nitrification　anammox　(PNA)　process.