This　study　focused　on　the　long-term　stability　of　a　novel　two-stage　partial-nitritation/anammox　(PN/A)　process　treating　municipal　wastewater　with　fluctuated　water　quality.　Specifically,　two　parallel　sequencing　batch　reactors　(SBRs)　were　used　for　removing　organic　matters　and　achieving　complete　nitritation,　while　the　expanded　granular　sludge　bed　(ANA-EGSB)　was　used　for　anammox.　With　the　influent　ammonium　concentration　varying　from　32　to　79　mg/L　and　the　average　hydraulic　retention　time　of　3.39　h　in　this　system,　more　than　93%　of　ammonium　was　removed　and　the　effluent　TIN　was　4.8-11.8　mg/L.　The　partial　denitrifying　occurring　in　the　anammox　reactor　could　reduce　nitrate　to　nitrite　that　was　reused　by　anammox　bacterium,　enhancing　the　TIN　removal　efficiency.　Further,　the　＂overconsumption　of　ammonium＂　under　anaerobic　conditions　was　observed　in　ANA-EGSB.　Microbial　community　analysis　showed　that　Nitrosomonas　(AOB)　were　the　dominant　nitrifying　bacteria　in　the　nitritation　SBR　and　Candidatus_Brocadia　with　the　relative　abundance　of　6-13%　dominated　in　ANA-EGSB.