A　two-stage　partial　nitritation/anammox　process　based　on　microbial　encapsulation　(PN/A-E)　was　established.　The　nitrogen　removal　characteristics　of　PN/A-E　under　high　and　low　ammonia　nitrogen　and　after　reactivation　following　a　long-term　shutdown　were　comprehensively　investigated　and　compared　with　anammox　granular　sludge　(AnGS).　The　stable　PN　process　did　not　depend　on　high　ammonia　nitrogen,　and　the　nitrite　accumulation　rate　reached　95.2　+/-　0.7　%.　The　overall　nitrogen　removal　rate　of　encapsulated　anammox　bacteria　was　twice　that　of　the　AnGS,　and　it　was　more　tolerant　to　external　interference.　Moreover,　PN/A-E　showed　good　reactivation　performance,　and　the　total　nitrogen　in　the　effluent　was　10.0　+/-　1.4　mg　center　dot　L-1　when　the　final　hydraulic　retention　time　was　2.18　h.　The　immobilized　fillers　support　an　increase　in　ammonia-oxidizing　bacteria　under　restricted　conditions　and　were　more　conducive　to　the　dominance　of　functional　bacteria　and　the　stability　of　microbial　community　under　low　ammonia　nitrogen.　This　study　provides　a　positive　method　to　achieve　a　reliable　PN/A.