In　this　study,　time-series　anammox　functional　biofilms　were　obtained　in　a　lab-scale　simultaneous　partial　nitritation/anammox　process　for　treating　high-strength　ammonium.　The　variations　in　the　biofilm　phenotypes,　community　succession,　and　anammox　bacteria　abundance　over　time　were　evaluated　using　optical　microscopy,　16S　rRNA　gene　sequencing,　and　qPCR.　The　result　revealed　that　biofilm　has　three　distinct　stages　of　the　community　development　trajectory　across　a　182-day　temporal　scale.　Anammox　bacteria　growth　rates　were　0.035　d(-1),　0.0015　d(-1),　and　0.011　d(-1),　respectively.　The　diversity　and　network　analysis　suggested　that　the　positive　priority　effect　of　ammonia　oxidizing　bacteria　was　the　primary　factor　for　the　rapid　proliferation　of　anammox　bacteria,　and　the　species　replacement　triggering　priority　effect　forfeiture　and　substituted　functional　recruitment　were　reasons　for　the　slow　proliferation　and　stable　proliferation　of　anammox　bacteria,　respectively.　Taken　together,　the　higher　microbial　diversity　and　stable　community　composite　were　key　prerequisites　for　the　proliferation　of　the　anammox　bacteria.